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| <a href="sketch_8sql__in.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/* ----------------------------------------------------------------------- */</span><span class="comment">/**</span></div> |
| <div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment"> *</span></div> |
| <div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment"> * @file sketch.sql_in</span></div> |
| <div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment"> *</span></div> |
| <div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment"> * @brief SQL functions for sketch-based approximations of descriptive statistics</span></div> |
| <div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"> * @date April 2011</span></div> |
| <div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"> *</span></div> |
| <div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment"> * @sa For a brief introduction to sketches, see the module description grp_sketches</span></div> |
| <div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment"> *</span></div> |
| <div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment"> */</span><span class="comment">/* ----------------------------------------------------------------------- */</span></div> |
| <div class="line"><a name="l00011"></a><span class="lineno"> 11</span> </div> |
| <div class="line"><a name="l00012"></a><span class="lineno"> 12</span> m4_include(`SQLCommon.m4<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment">@addtogroup grp_sketches</span></div> |
| <div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment">\warning <em> This MADlib method is still in early stage development. There may be some </span></div> |
| <div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment">issues that will be addressed in a future version. Interface and implementation</span></div> |
| <div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="comment">is subject to change. </em></span></div> |
| <div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment">@about</span></div> |
| <div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment">Sketches (sometimes called "synopsis data structures") are small randomized</span></div> |
| <div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment">in-memory data structures that capture statistical properties of a large set</span></div> |
| <div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment">of values (e.g. a column of a table). Sketches can be formed in a single</span></div> |
| <div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment">pass of the data, and used to approximate a variety of descriptive statistics.</span></div> |
| <div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment">We implement sketches as SQL User-Defined Aggregates (UDAs). Because they</span></div> |
| <div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">are single-pass, small-space and parallelized, a single query can</span></div> |
| <div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="comment">use many sketches to gather summary statistics on many columns of a table efficiently.</span></div> |
| <div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="comment">This module currently implements user-defined aggregates based on three main sketch methods:</span></div> |
| <div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="comment"> - <i>Flajolet-Martin (FM)</i> sketches for approximating <c>COUNT(DISTINCT)</c>.</span></div> |
| <div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="comment"> - <i>Count-Min (CM)</i> sketches, which can be used to approximate a number of descriptive statistics including</span></div> |
| <div class="line"><a name="l00035"></a><span class="lineno"> 35</span> <span class="comment"> - <c>COUNT(*)</c> of rows whose column value matches a given value in a set</span></div> |
| <div class="line"><a name="l00036"></a><span class="lineno"> 36</span> <span class="comment"> - <c>COUNT(*)</c> of rows whose column value falls in a range (*)</span></div> |
| <div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment"> - order statistics including <i>median</i> and <i>centiles</i> (*)</span></div> |
| <div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment"> - <i>histograms</i>: both <i>equi-width</i> and <i>equi-depth</i> (*)</span></div> |
| <div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment"> - <i>Most Frequent Value (MFV)</i> sketches, which output the most</span></div> |
| <div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment">frequently-occuring values in a column, along with their associated counts.</span></div> |
| <div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment"> <i>Note:</i> Features marked with a star (*) only work for discrete types that</span></div> |
| <div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment"> can be cast to int8.</span></div> |
| <div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment">@implementation</span></div> |
| <div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="comment">The sketch methods consists of a number of SQL UDAs (user defined aggregates)</span></div> |
| <div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="comment">and UDFs (user defined functions), to be used directly in SQL queries.</span></div> |
| <div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="comment">@addtogroup grp_fmsketch</span></div> |
| <div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="comment">\warning <em> This MADlib method is still in early stage development. There may be some </span></div> |
| <div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="comment">issues that will be addressed in a future version. Interface and implementation</span></div> |
| <div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment">is subject to change. </em></span></div> |
| <div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment">@about</span></div> |
| <div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment">Flajolet-Martin's distinct count estimation</span></div> |
| <div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment">implemented as a user-defined aggregate.</span></div> |
| <div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment">@usage</span></div> |
| <div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment">- Get the number of distinct values in a designated column.</span></div> |
| <div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment"> <pre>SELECT \ref fmsketch_dcount(<em>col_name</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment">@implementation</span></div> |
| <div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment">\ref fmsketch_dcount can be run on a column of any type.</span></div> |
| <div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment">It returns an approximation to the number of distinct values</span></div> |
| <div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment">(a la <c>COUNT(DISTINCT x)</c>), but faster and approximate.</span></div> |
| <div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment">Like any aggregate, it can be combined with a GROUP BY clause to do distinct</span></div> |
| <div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment">counts per group.</span></div> |
| <div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="comment">@examp</span></div> |
| <div class="line"><a name="l00073"></a><span class="lineno"> 73</span> <span class="comment">-# Generate some data:</span></div> |
| <div class="line"><a name="l00074"></a><span class="lineno"> 74</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00075"></a><span class="lineno"> 75</span> <span class="comment">sql> CREATE TABLE data(class INT, a1 INT);</span></div> |
| <div class="line"><a name="l00076"></a><span class="lineno"> 76</span> <span class="comment">sql> INSERT INTO data SELECT 1,1 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00077"></a><span class="lineno"> 77</span> <span class="comment">sql> INSERT INTO data SELECT 1,2 FROM generate_series(1,15000);</span></div> |
| <div class="line"><a name="l00078"></a><span class="lineno"> 78</span> <span class="comment">sql> INSERT INTO data SELECT 1,3 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00079"></a><span class="lineno"> 79</span> <span class="comment">sql> INSERT INTO data SELECT 2,5 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00080"></a><span class="lineno"> 80</span> <span class="comment">sql> INSERT INTO data SELECT 2,6 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00081"></a><span class="lineno"> 81</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00082"></a><span class="lineno"> 82</span> <span class="comment">-# Find distinct number of values for each class</span></div> |
| <div class="line"><a name="l00083"></a><span class="lineno"> 83</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00084"></a><span class="lineno"> 84</span> <span class="comment">sql> SELECT class,fmsketch_dcount(a1) FROM data GROUP BY data.class;</span></div> |
| <div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="comment">class | fmsketch_dcount</span></div> |
| <div class="line"><a name="l00086"></a><span class="lineno"> 86</span> <span class="comment">-------+-----------------</span></div> |
| <div class="line"><a name="l00087"></a><span class="lineno"> 87</span> <span class="comment"> 2 | 2</span></div> |
| <div class="line"><a name="l00088"></a><span class="lineno"> 88</span> <span class="comment"> 1 | 3</span></div> |
| <div class="line"><a name="l00089"></a><span class="lineno"> 89</span> <span class="comment">(2 rows)</span></div> |
| <div class="line"><a name="l00090"></a><span class="lineno"> 90</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00091"></a><span class="lineno"> 91</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00092"></a><span class="lineno"> 92</span> <span class="comment">@literature</span></div> |
| <div class="line"><a name="l00093"></a><span class="lineno"> 93</span> <span class="comment">[1] P. Flajolet and N.G. Martin. Probabilistic counting algorithms for data base applications, Journal of Computer and System Sciences 31(2), pp 182-209, 1985. http://algo.inria.fr/flajolet/Publications/FlMa85.pdf</span></div> |
| <div class="line"><a name="l00094"></a><span class="lineno"> 94</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00095"></a><span class="lineno"> 95</span> <span class="comment">@sa File sketch.sql_in documenting the SQL function.</span></div> |
| <div class="line"><a name="l00096"></a><span class="lineno"> 96</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00097"></a><span class="lineno"> 97</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00098"></a><span class="lineno"> 98</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00099"></a><span class="lineno"> 99</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00100"></a><span class="lineno"> 100</span> <span class="comment">@addtogroup grp_countmin</span></div> |
| <div class="line"><a name="l00101"></a><span class="lineno"> 101</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00102"></a><span class="lineno"> 102</span> <span class="comment">\warning <em> This MADlib method is still in early stage development. There may be some </span></div> |
| <div class="line"><a name="l00103"></a><span class="lineno"> 103</span> <span class="comment">issues that will be addressed in a future version. Interface and implementation</span></div> |
| <div class="line"><a name="l00104"></a><span class="lineno"> 104</span> <span class="comment">is subject to change. </em></span></div> |
| <div class="line"><a name="l00105"></a><span class="lineno"> 105</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00106"></a><span class="lineno"> 106</span> <span class="comment">@about</span></div> |
| <div class="line"><a name="l00107"></a><span class="lineno"> 107</span> <span class="comment">This module implements Cormode-Muthukrishnan <i>CountMin</i> sketches</span></div> |
| <div class="line"><a name="l00108"></a><span class="lineno"> 108</span> <span class="comment">on integer values, implemented as a user-defined aggregate. It also provides</span></div> |
| <div class="line"><a name="l00109"></a><span class="lineno"> 109</span> <span class="comment">scalar functions over the sketches to produce approximate counts, order</span></div> |
| <div class="line"><a name="l00110"></a><span class="lineno"> 110</span> <span class="comment">statistics, and histograms.</span></div> |
| <div class="line"><a name="l00111"></a><span class="lineno"> 111</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00112"></a><span class="lineno"> 112</span> <span class="comment">@usage</span></div> |
| <div class="line"><a name="l00113"></a><span class="lineno"> 113</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00114"></a><span class="lineno"> 114</span> <span class="comment">- Get a sketch of a selected column specified by <em>col_name</em>.</span></div> |
| <div class="line"><a name="l00115"></a><span class="lineno"> 115</span> <span class="comment"> <pre>SELECT \ref cmsketch(<em>col_name</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00116"></a><span class="lineno"> 116</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00117"></a><span class="lineno"> 117</span> <span class="comment">- Get the number of rows where <em>col_name = p</em>, computed from the sketch</span></div> |
| <div class="line"><a name="l00118"></a><span class="lineno"> 118</span> <span class="comment"> obtained from <tt>cmsketch</tt>.</span></div> |
| <div class="line"><a name="l00119"></a><span class="lineno"> 119</span> <span class="comment"> <pre>SELECT \ref cmsketch_count(<em>cmsketch</em>,<em>p</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00120"></a><span class="lineno"> 120</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00121"></a><span class="lineno"> 121</span> <span class="comment">- Get the number of rows where <em>col_name</em> is between <em>m</em> and <em>n</em> inclusive.</span></div> |
| <div class="line"><a name="l00122"></a><span class="lineno"> 122</span> <span class="comment"> <pre>SELECT \ref cmsketch_rangecount(<em>cmsketch</em>,<em>m</em>,<em>n</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00123"></a><span class="lineno"> 123</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00124"></a><span class="lineno"> 124</span> <span class="comment">- Get the <em>k</em>th percentile of <em>col_name</em> where <em>count</em> specifies number of rows. <em>k</em> should be an integer between 1 to 99.</span></div> |
| <div class="line"><a name="l00125"></a><span class="lineno"> 125</span> <span class="comment"> <pre>SELECT \ref cmsketch_centile(<em>cmsketch</em>,<em>k</em>,<em>count</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00126"></a><span class="lineno"> 126</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00127"></a><span class="lineno"> 127</span> <span class="comment">- Get the median of <em>col_name</em> where <em>count</em> specifies number of rows. This is equivalent to <tt>\ref cmsketch_centile(<em>cmsketch</em>,50,<em>count</em>)</tt>.</span></div> |
| <div class="line"><a name="l00128"></a><span class="lineno"> 128</span> <span class="comment"> <pre>SELECT \ref cmsketch_median(<em>cmsketch</em>,<em>count</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00129"></a><span class="lineno"> 129</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00130"></a><span class="lineno"> 130</span> <span class="comment">- Get an n-bucket histogram for values between min and max for the column where each bucket has approximately the same width. The output is a text string containing triples {lo, hi, count} representing the buckets; counts are approximate.</span></div> |
| <div class="line"><a name="l00131"></a><span class="lineno"> 131</span> <span class="comment"> <pre>SELECT \ref cmsketch_width_histogram(<em>cmsketch</em>,<em>min</em>,<em>max</em>,<em>n</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00132"></a><span class="lineno"> 132</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00133"></a><span class="lineno"> 133</span> <span class="comment">- Get an n-bucket histogram for the column where each bucket has approximately the same count. The output is a text string containing triples {lo, hi, count} representing the buckets; counts are approximate. Note that an equi-depth histogram is equivalent to a spanning set of equi-spaced centiles.</span></div> |
| <div class="line"><a name="l00134"></a><span class="lineno"> 134</span> <span class="comment"> <pre>SELECT \ref cmsketch_depth_histogram(<em>cmsketch</em>,<em>n</em>) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00135"></a><span class="lineno"> 135</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00136"></a><span class="lineno"> 136</span> <span class="comment">@examp</span></div> |
| <div class="line"><a name="l00137"></a><span class="lineno"> 137</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00138"></a><span class="lineno"> 138</span> <span class="comment">-# Generate some data</span></div> |
| <div class="line"><a name="l00139"></a><span class="lineno"> 139</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00140"></a><span class="lineno"> 140</span> <span class="comment">sql> CREATE TABLE data(class INT, a1 INT);</span></div> |
| <div class="line"><a name="l00141"></a><span class="lineno"> 141</span> <span class="comment">sql> INSERT INTO data SELECT 1,1 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00142"></a><span class="lineno"> 142</span> <span class="comment">sql> INSERT INTO data SELECT 1,2 FROM generate_series(1,15000);</span></div> |
| <div class="line"><a name="l00143"></a><span class="lineno"> 143</span> <span class="comment">sql> INSERT INTO data SELECT 1,3 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00144"></a><span class="lineno"> 144</span> <span class="comment">sql> INSERT INTO data SELECT 2,5 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00145"></a><span class="lineno"> 145</span> <span class="comment">sql> INSERT INTO data SELECT 2,6 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00146"></a><span class="lineno"> 146</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00147"></a><span class="lineno"> 147</span> <span class="comment">-# Count number of rows where a1 = 2 in each class</span></div> |
| <div class="line"><a name="l00148"></a><span class="lineno"> 148</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00149"></a><span class="lineno"> 149</span> <span class="comment">sql> SELECT class,cmsketch_count(cmsketch(a1),2) FROM data GROUP BY data.class;</span></div> |
| <div class="line"><a name="l00150"></a><span class="lineno"> 150</span> <span class="comment"> class | cmsketch_count</span></div> |
| <div class="line"><a name="l00151"></a><span class="lineno"> 151</span> <span class="comment">-------+----------------</span></div> |
| <div class="line"><a name="l00152"></a><span class="lineno"> 152</span> <span class="comment"> 2 | 0</span></div> |
| <div class="line"><a name="l00153"></a><span class="lineno"> 153</span> <span class="comment"> 1 | 15000</span></div> |
| <div class="line"><a name="l00154"></a><span class="lineno"> 154</span> <span class="comment">(2 rows)</span></div> |
| <div class="line"><a name="l00155"></a><span class="lineno"> 155</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00156"></a><span class="lineno"> 156</span> <span class="comment">-# Count number of rows where a1 is between 3 and 6</span></div> |
| <div class="line"><a name="l00157"></a><span class="lineno"> 157</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00158"></a><span class="lineno"> 158</span> <span class="comment">sql> SELECT class,cmsketch_rangecount(cmsketch(a1),3,6) FROM data GROUP BY data.class;</span></div> |
| <div class="line"><a name="l00159"></a><span class="lineno"> 159</span> <span class="comment"> class | cmsketch_rangecount</span></div> |
| <div class="line"><a name="l00160"></a><span class="lineno"> 160</span> <span class="comment">-------+---------------------</span></div> |
| <div class="line"><a name="l00161"></a><span class="lineno"> 161</span> <span class="comment"> 2 | 2000</span></div> |
| <div class="line"><a name="l00162"></a><span class="lineno"> 162</span> <span class="comment"> 1 | 10000</span></div> |
| <div class="line"><a name="l00163"></a><span class="lineno"> 163</span> <span class="comment">(2 rows)</span></div> |
| <div class="line"><a name="l00164"></a><span class="lineno"> 164</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00165"></a><span class="lineno"> 165</span> <span class="comment">-# Compute the 90th percentile of all of a1</span></div> |
| <div class="line"><a name="l00166"></a><span class="lineno"> 166</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00167"></a><span class="lineno"> 167</span> <span class="comment">sql> SELECT cmsketch_centile(cmsketch(a1),90,count(*)) FROM data;</span></div> |
| <div class="line"><a name="l00168"></a><span class="lineno"> 168</span> <span class="comment"> cmsketch_centile</span></div> |
| <div class="line"><a name="l00169"></a><span class="lineno"> 169</span> <span class="comment">------------------</span></div> |
| <div class="line"><a name="l00170"></a><span class="lineno"> 170</span> <span class="comment"> 3</span></div> |
| <div class="line"><a name="l00171"></a><span class="lineno"> 171</span> <span class="comment">(1 row)</span></div> |
| <div class="line"><a name="l00172"></a><span class="lineno"> 172</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00173"></a><span class="lineno"> 173</span> <span class="comment">-# Produce an equi-width histogram with 2 bins between 0 and 10</span></div> |
| <div class="line"><a name="l00174"></a><span class="lineno"> 174</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00175"></a><span class="lineno"> 175</span> <span class="comment">sql> SELECT cmsketch_width_histogram(cmsketch(a1),0,10,2) FROM data;</span></div> |
| <div class="line"><a name="l00176"></a><span class="lineno"> 176</span> <span class="comment"> cmsketch_width_histogram</span></div> |
| <div class="line"><a name="l00177"></a><span class="lineno"> 177</span> <span class="comment">------------------------------------</span></div> |
| <div class="line"><a name="l00178"></a><span class="lineno"> 178</span> <span class="comment"> [[0L, 4L, 35000], [5L, 10L, 2000]]</span></div> |
| <div class="line"><a name="l00179"></a><span class="lineno"> 179</span> <span class="comment">(1 row)</span></div> |
| <div class="line"><a name="l00180"></a><span class="lineno"> 180</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00181"></a><span class="lineno"> 181</span> <span class="comment">-# Produce an equi-depth histogram of a1 with 2 bins of approximately equal depth</span></div> |
| <div class="line"><a name="l00182"></a><span class="lineno"> 182</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00183"></a><span class="lineno"> 183</span> <span class="comment">sql> SELECT cmsketch_depth_histogram(cmsketch(a1),2) FROM data;</span></div> |
| <div class="line"><a name="l00184"></a><span class="lineno"> 184</span> <span class="comment"> cmsketch_depth_histogram</span></div> |
| <div class="line"><a name="l00185"></a><span class="lineno"> 185</span> <span class="comment">-----------------------------------------------------------------------</span></div> |
| <div class="line"><a name="l00186"></a><span class="lineno"> 186</span> <span class="comment"> [[-9223372036854775807L, 1, 10000], [2, 9223372036854775807L, 27000]]</span></div> |
| <div class="line"><a name="l00187"></a><span class="lineno"> 187</span> <span class="comment">(1 row)</span></div> |
| <div class="line"><a name="l00188"></a><span class="lineno"> 188</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00189"></a><span class="lineno"> 189</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00190"></a><span class="lineno"> 190</span> <span class="comment">@literature</span></div> |
| <div class="line"><a name="l00191"></a><span class="lineno"> 191</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00192"></a><span class="lineno"> 192</span> <span class="comment">[1] G. Cormode and S. Muthukrishnan. An improved data stream summary: The count-min sketch and its applications. LATIN 2004, J. Algorithm 55(1): 58-75 (2005) . http://dimacs.rutgers.edu/~graham/pubs/html/CormodeMuthukrishnan04CMLatin.html</span></div> |
| <div class="line"><a name="l00193"></a><span class="lineno"> 193</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00194"></a><span class="lineno"> 194</span> <span class="comment">[2] G. Cormode. Encyclopedia entry on 'Count-Min Sketch'. In L. Liu and M. T. Ozsu, editors, Encyclopedia of Database Systems, pages 511-516. Springer, 2009. http://dimacs.rutgers.edu/~graham/pubs/html/Cormode09b.html</span></div> |
| <div class="line"><a name="l00195"></a><span class="lineno"> 195</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00196"></a><span class="lineno"> 196</span> <span class="comment">@sa File sketch.sql_in documenting the SQL functions.</span></div> |
| <div class="line"><a name="l00197"></a><span class="lineno"> 197</span> <span class="comment">\n\n Module grp_quantile for a different implementation of quantile function.</span></div> |
| <div class="line"><a name="l00198"></a><span class="lineno"> 198</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00199"></a><span class="lineno"> 199</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00200"></a><span class="lineno"> 200</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00201"></a><span class="lineno"> 201</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00202"></a><span class="lineno"> 202</span> <span class="comment">@addtogroup grp_mfvsketch</span></div> |
| <div class="line"><a name="l00203"></a><span class="lineno"> 203</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00204"></a><span class="lineno"> 204</span> <span class="comment">\warning <em> This MADlib method is still in early stage development. There may be some </span></div> |
| <div class="line"><a name="l00205"></a><span class="lineno"> 205</span> <span class="comment">issues that will be addressed in a future version. Interface and implementation</span></div> |
| <div class="line"><a name="l00206"></a><span class="lineno"> 206</span> <span class="comment">is subject to change. </em></span></div> |
| <div class="line"><a name="l00207"></a><span class="lineno"> 207</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00208"></a><span class="lineno"> 208</span> <span class="comment">@about</span></div> |
| <div class="line"><a name="l00209"></a><span class="lineno"> 209</span> <span class="comment">MFVSketch: Most Frequent Values variant of CountMin sketch, implemented</span></div> |
| <div class="line"><a name="l00210"></a><span class="lineno"> 210</span> <span class="comment">as a UDA.</span></div> |
| <div class="line"><a name="l00211"></a><span class="lineno"> 211</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00212"></a><span class="lineno"> 212</span> <span class="comment">@usage</span></div> |
| <div class="line"><a name="l00213"></a><span class="lineno"> 213</span> <span class="comment">Produces an n-bucket histogram for a column where each bucket counts one of the</span></div> |
| <div class="line"><a name="l00214"></a><span class="lineno"> 214</span> <span class="comment">most frequent values in the column. The output is an array of doubles {value, count}</span></div> |
| <div class="line"><a name="l00215"></a><span class="lineno"> 215</span> <span class="comment">in descending order of frequency; counts are approximated via CountMin sketches.</span></div> |
| <div class="line"><a name="l00216"></a><span class="lineno"> 216</span> <span class="comment">Ties are handled arbitrarily.</span></div> |
| <div class="line"><a name="l00217"></a><span class="lineno"> 217</span> <span class="comment"><pre>SELECT \ref mfvsketch_top_histogram(<em>col_name</em>,n) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00218"></a><span class="lineno"> 218</span> <span class="comment"><pre>SELECT \ref mfvsketch_top_histogram(<em>col_name</em>,n) FROM table_name;</pre></span></div> |
| <div class="line"><a name="l00219"></a><span class="lineno"> 219</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00220"></a><span class="lineno"> 220</span> <span class="comment">The MFV frequent-value UDA comes in two different versions:</span></div> |
| <div class="line"><a name="l00221"></a><span class="lineno"> 221</span> <span class="comment">- a faithful implementation that preserves the approximation guarantees</span></div> |
| <div class="line"><a name="l00222"></a><span class="lineno"> 222</span> <span class="comment">of Cormode/Muthukrishnan,</span></div> |
| <div class="line"><a name="l00223"></a><span class="lineno"> 223</span> <span class="comment">- and a "quick and dirty" version that can do parallel aggregation in Greenplum</span></div> |
| <div class="line"><a name="l00224"></a><span class="lineno"> 224</span> <span class="comment">at the expense of missing some of the most frequent values.</span></div> |
| <div class="line"><a name="l00225"></a><span class="lineno"> 225</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00226"></a><span class="lineno"> 226</span> <span class="comment">In PostgreSQL the two UDAs are identical. In Greenplum, the quick version should</span></div> |
| <div class="line"><a name="l00227"></a><span class="lineno"> 227</span> <span class="comment">produce good results unless the number of values requested is very small,</span></div> |
| <div class="line"><a name="l00228"></a><span class="lineno"> 228</span> <span class="comment">or the distribution is very flat.</span></div> |
| <div class="line"><a name="l00229"></a><span class="lineno"> 229</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00230"></a><span class="lineno"> 230</span> <span class="comment">@examp</span></div> |
| <div class="line"><a name="l00231"></a><span class="lineno"> 231</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00232"></a><span class="lineno"> 232</span> <span class="comment">-# Generate some data</span></div> |
| <div class="line"><a name="l00233"></a><span class="lineno"> 233</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00234"></a><span class="lineno"> 234</span> <span class="comment">sql> CREATE TABLE data(class INT, a1 INT);</span></div> |
| <div class="line"><a name="l00235"></a><span class="lineno"> 235</span> <span class="comment">sql> INSERT INTO data SELECT 1,1 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00236"></a><span class="lineno"> 236</span> <span class="comment">sql> INSERT INTO data SELECT 1,2 FROM generate_series(1,15000);</span></div> |
| <div class="line"><a name="l00237"></a><span class="lineno"> 237</span> <span class="comment">sql> INSERT INTO data SELECT 1,3 FROM generate_series(1,10000);</span></div> |
| <div class="line"><a name="l00238"></a><span class="lineno"> 238</span> <span class="comment">sql> INSERT INTO data SELECT 2,5 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00239"></a><span class="lineno"> 239</span> <span class="comment">sql> INSERT INTO data SELECT 2,6 FROM generate_series(1,1000);</span></div> |
| <div class="line"><a name="l00240"></a><span class="lineno"> 240</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00241"></a><span class="lineno"> 241</span> <span class="comment">-# Produce histogram of 5 bins and return the most frequent value and associated</span></div> |
| <div class="line"><a name="l00242"></a><span class="lineno"> 242</span> <span class="comment">count in each bin:</span></div> |
| <div class="line"><a name="l00243"></a><span class="lineno"> 243</span> <span class="comment">\verbatim</span></div> |
| <div class="line"><a name="l00244"></a><span class="lineno"> 244</span> <span class="comment">sql> SELECT mfvsketch_top_histogram(a1,5) FROM data;</span></div> |
| <div class="line"><a name="l00245"></a><span class="lineno"> 245</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00246"></a><span class="lineno"> 246</span> <span class="comment"> mfvsketch_top_histogram</span></div> |
| <div class="line"><a name="l00247"></a><span class="lineno"> 247</span> <span class="comment">--------------------------------------------------------------</span></div> |
| <div class="line"><a name="l00248"></a><span class="lineno"> 248</span> <span class="comment">[0:4][0:1]={{2,15000},{1,10000},{3,10000},{5,1000},{6,1000}}</span></div> |
| <div class="line"><a name="l00249"></a><span class="lineno"> 249</span> <span class="comment">(1 row)</span></div> |
| <div class="line"><a name="l00250"></a><span class="lineno"> 250</span> <span class="comment">\endverbatim</span></div> |
| <div class="line"><a name="l00251"></a><span class="lineno"> 251</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00252"></a><span class="lineno"> 252</span> <span class="comment">@literature</span></div> |
| <div class="line"><a name="l00253"></a><span class="lineno"> 253</span> <span class="comment">This method is not usually called an MFV sketch in the literature; it</span></div> |
| <div class="line"><a name="l00254"></a><span class="lineno"> 254</span> <span class="comment">is a natural extension of the CountMin sketch.</span></div> |
| <div class="line"><a name="l00255"></a><span class="lineno"> 255</span> <span class="comment"></span></div> |
| <div class="line"><a name="l00256"></a><span class="lineno"> 256</span> <span class="comment">@sa File sketch.sql_in documenting the SQL functions.</span></div> |
| <div class="line"><a name="l00257"></a><span class="lineno"> 257</span> <span class="comment">\n\n Module grp_countmin.</span></div> |
| <div class="line"><a name="l00258"></a><span class="lineno"> 258</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00259"></a><span class="lineno"> 259</span> </div> |
| <div class="line"><a name="l00260"></a><span class="lineno"> 260</span> -- FM Sketch Functions</div> |
| <div class="line"><a name="l00261"></a><span class="lineno"> 261</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.big_or(bitmap1 bytea, bitmap2 bytea) CASCADE;</div> |
| <div class="line"><a name="l00262"></a><span class="lineno"> 262</span> CREATE FUNCTION MADLIB_SCHEMA.big_or(bitmap1 bytea, bitmap2 bytea)</div> |
| <div class="line"><a name="l00263"></a><span class="lineno"> 263</span> RETURNS bytea</div> |
| <div class="line"><a name="l00264"></a><span class="lineno"> 264</span> AS 'MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00265"></a><span class="lineno"> 265</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00266"></a><span class="lineno"> 266</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00267"></a><span class="lineno"> 267</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__fmsketch_trans(bitmaps bytea, input anyelement) CASCADE;</span></div> |
| <div class="line"><a name="l00268"></a><span class="lineno"> 268</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__fmsketch_trans(bitmaps bytea, input anyelement)</span></div> |
| <div class="line"><a name="l00269"></a><span class="lineno"> 269</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00270"></a><span class="lineno"> 270</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00271"></a><span class="lineno"> 271</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00272"></a><span class="lineno"> 272</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00273"></a><span class="lineno"> 273</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__fmsketch_count_distinct(bitmaps bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00274"></a><span class="lineno"> 274</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__fmsketch_count_distinct(bitmaps bytea)</span></div> |
| <div class="line"><a name="l00275"></a><span class="lineno"> 275</span> <span class="stringliteral">RETURNS int8</span></div> |
| <div class="line"><a name="l00276"></a><span class="lineno"> 276</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00277"></a><span class="lineno"> 277</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00278"></a><span class="lineno"> 278</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00279"></a><span class="lineno"> 279</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__fmsketch_merge(bitmaps1 bytea, bitmaps2 bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00280"></a><span class="lineno"> 280</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__fmsketch_merge(bitmaps1 bytea, bitmaps2 bytea)</span></div> |
| <div class="line"><a name="l00281"></a><span class="lineno"> 281</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00282"></a><span class="lineno"> 282</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00283"></a><span class="lineno"> 283</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00284"></a><span class="lineno"> 284</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00285"></a><span class="lineno"> 285</span> <span class="stringliteral">DROP AGGREGATE IF EXISTS MADLIB_SCHEMA.fmsketch_dcount(anyelement);</span></div> |
| <div class="line"><a name="l00286"></a><span class="lineno"> 286</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00287"></a><span class="lineno"> 287</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00288"></a><span class="lineno"> 288</span> <span class="comment"> * @brief Flajolet-Martin's distinct count estimation</span></div> |
| <div class="line"><a name="l00289"></a><span class="lineno"> 289</span> <span class="comment"> * @param column name</span></div> |
| <div class="line"><a name="l00290"></a><span class="lineno"> 290</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00291"></a><span class="lineno"> 291</span> CREATE AGGREGATE MADLIB_SCHEMA.fmsketch_dcount(/*+ column */ anyelement)</div> |
| <div class="line"><a name="l00292"></a><span class="lineno"> 292</span> (</div> |
| <div class="line"><a name="l00293"></a><span class="lineno"> 293</span>  sfunc = MADLIB_SCHEMA.__fmsketch_trans,</div> |
| <div class="line"><a name="l00294"></a><span class="lineno"> 294</span>  stype = bytea,</div> |
| <div class="line"><a name="l00295"></a><span class="lineno"> 295</span>  finalfunc = MADLIB_SCHEMA.__fmsketch_count_distinct,</div> |
| <div class="line"><a name="l00296"></a><span class="lineno"> 296</span>  m4_ifdef(`__GREENPLUM__',`prefunc = MADLIB_SCHEMA.__fmsketch_merge,<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00297"></a><span class="lineno"> 297</span> <span class="stringliteral"> initcond = '</span><span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00298"></a><span class="lineno"> 298</span> <span class="stringliteral">);</span></div> |
| <div class="line"><a name="l00299"></a><span class="lineno"> 299</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00300"></a><span class="lineno"> 300</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00301"></a><span class="lineno"> 301</span> <span class="stringliteral">-- CM Sketch Functions</span></div> |
| <div class="line"><a name="l00302"></a><span class="lineno"> 302</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00303"></a><span class="lineno"> 303</span> <span class="stringliteral">-- We register __cmsketch_int8_trans for varying numbers of arguments to support</span></div> |
| <div class="line"><a name="l00304"></a><span class="lineno"> 304</span> <span class="stringliteral">-- a variety of agg function signatures. The first 2 args are used to</span></div> |
| <div class="line"><a name="l00305"></a><span class="lineno"> 305</span> <span class="stringliteral">-- aggregate; the remaining args are carried along unchanged inside the</span></div> |
| <div class="line"><a name="l00306"></a><span class="lineno"> 306</span> <span class="stringliteral">-- return structure for the use of the UDA finalizer.</span></div> |
| <div class="line"><a name="l00307"></a><span class="lineno"> 307</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_int8_trans(bytea, int8) CASCADE;</span></div> |
| <div class="line"><a name="l00308"></a><span class="lineno"> 308</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_int8_trans(bitmaps bytea, input int8)</span></div> |
| <div class="line"><a name="l00309"></a><span class="lineno"> 309</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00310"></a><span class="lineno"> 310</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00311"></a><span class="lineno"> 311</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00312"></a><span class="lineno"> 312</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00313"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a5a7e077028d5e0441552a77db3586db1"> 313</a></span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_int8_trans(bytea, int8, int8) CASCADE;</span></div> |
| <div class="line"><a name="l00314"></a><span class="lineno"> 314</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_int8_trans(bitmaps bytea, input int8, arg1 int8)</span></div> |
| <div class="line"><a name="l00315"></a><span class="lineno"> 315</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00316"></a><span class="lineno"> 316</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00317"></a><span class="lineno"> 317</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00318"></a><span class="lineno"> 318</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00319"></a><span class="lineno"> 319</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_int8_trans(bytea, int8, int8, int8) CASCADE;</span></div> |
| <div class="line"><a name="l00320"></a><span class="lineno"> 320</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_int8_trans(bitmaps bytea, input int8, arg1 int8, arg2 int8)</span></div> |
| <div class="line"><a name="l00321"></a><span class="lineno"> 321</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00322"></a><span class="lineno"> 322</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00323"></a><span class="lineno"> 323</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00324"></a><span class="lineno"> 324</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00325"></a><span class="lineno"> 325</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_int8_trans(bytea, int8, int8, int8, int8) CASCADE;</span></div> |
| <div class="line"><a name="l00326"></a><span class="lineno"> 326</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_int8_trans(bitmaps bytea, input int8, arg1 int8, arg2 int8, arg3 int8)</span></div> |
| <div class="line"><a name="l00327"></a><span class="lineno"> 327</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00328"></a><span class="lineno"> 328</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00329"></a><span class="lineno"> 329</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00330"></a><span class="lineno"> 330</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00331"></a><span class="lineno"> 331</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_final(bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00332"></a><span class="lineno"> 332</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_final(counters bytea)</span></div> |
| <div class="line"><a name="l00333"></a><span class="lineno"> 333</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00334"></a><span class="lineno"> 334</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00335"></a><span class="lineno"> 335</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00336"></a><span class="lineno"> 336</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00337"></a><span class="lineno"> 337</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_base64_final(bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00338"></a><span class="lineno"> 338</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_base64_final(sketch bytea)</span></div> |
| <div class="line"><a name="l00339"></a><span class="lineno"> 339</span> <span class="stringliteral">RETURNS text</span></div> |
| <div class="line"><a name="l00340"></a><span class="lineno"> 340</span> <span class="stringliteral">AS $$</span></div> |
| <div class="line"><a name="l00341"></a><span class="lineno"> 341</span> <span class="stringliteral">select encode(MADLIB_SCHEMA.__cmsketch_final($1), '</span>base64<span class="stringliteral">');</span></div> |
| <div class="line"><a name="l00342"></a><span class="lineno"> 342</span> <span class="stringliteral">$$ LANGUAGE SQL;</span></div> |
| <div class="line"><a name="l00343"></a><span class="lineno"> 343</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00344"></a><span class="lineno"> 344</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__cmsketch_merge(bytea, bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00345"></a><span class="lineno"> 345</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__cmsketch_merge(bytea, bytea)</span></div> |
| <div class="line"><a name="l00346"></a><span class="lineno"> 346</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00347"></a><span class="lineno"> 347</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00348"></a><span class="lineno"> 348</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00349"></a><span class="lineno"> 349</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00350"></a><span class="lineno"> 350</span> <span class="stringliteral">DROP AGGREGATE IF EXISTS MADLIB_SCHEMA.cmsketch(int8);</span><span class="comment"></span></div> |
| <div class="line"><a name="l00351"></a><span class="lineno"> 351</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00352"></a><span class="lineno"> 352</span> <span class="comment"> *@brief <c>cmsketch</c> is a UDA that can be run on columns of type int8,</span></div> |
| <div class="line"><a name="l00353"></a><span class="lineno"> 353</span> <span class="comment"> * or any column that can be cast to an int8. It produces a base64 string</span></div> |
| <div class="line"><a name="l00354"></a><span class="lineno"> 354</span> <span class="comment"> * representing a CountMin sketch: a large array of counters that is intended</span></div> |
| <div class="line"><a name="l00355"></a><span class="lineno"> 355</span> <span class="comment"> * to be passed into a UDF like <c>cmsketch_width_histogram</c> described below.</span></div> |
| <div class="line"><a name="l00356"></a><span class="lineno"> 356</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00357"></a><span class="lineno"> 357</span> CREATE AGGREGATE MADLIB_SCHEMA.cmsketch(/*+ column */ INT8)</div> |
| <div class="line"><a name="l00358"></a><span class="lineno"> 358</span> (</div> |
| <div class="line"><a name="l00359"></a><span class="lineno"> 359</span>  sfunc = MADLIB_SCHEMA.__cmsketch_int8_trans,</div> |
| <div class="line"><a name="l00360"></a><span class="lineno"> 360</span>  stype = bytea,</div> |
| <div class="line"><a name="l00361"></a><span class="lineno"> 361</span>  finalfunc = MADLIB_SCHEMA.__cmsketch_base64_final,</div> |
| <div class="line"><a name="l00362"></a><span class="lineno"> 362</span>  m4_ifdef(`__GREENPLUM__', `prefunc = MADLIB_SCHEMA.__cmsketch_merge,<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00363"></a><span class="lineno"> 363</span> <span class="stringliteral"> initcond = '</span><span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00364"></a><span class="lineno"> 364</span> <span class="stringliteral">);</span></div> |
| <div class="line"><a name="l00365"></a><span class="lineno"> 365</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00366"></a><span class="lineno"> 366</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00367"></a><span class="lineno"> 367</span> <span class="comment"> @brief <c>cmsketch_count</c> is a scalar UDF to compute the approximate</span></div> |
| <div class="line"><a name="l00368"></a><span class="lineno"> 368</span> <span class="comment"> number of occurences of a value in a column summarized by a cmsketch. Takes</span></div> |
| <div class="line"><a name="l00369"></a><span class="lineno"> 369</span> <span class="comment"> the results of the <c>cmsketch</c> aggregate as its first argument, and the</span></div> |
| <div class="line"><a name="l00370"></a><span class="lineno"> 370</span> <span class="comment"> desired value as the second.</span></div> |
| <div class="line"><a name="l00371"></a><span class="lineno"> 371</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00372"></a><span class="lineno"> 372</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_count(text, int8) CASCADE;</div> |
| <div class="line"><a name="l00373"></a><span class="lineno"> 373</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_count(sketches64 text, val int8)</div> |
| <div class="line"><a name="l00374"></a><span class="lineno"> 374</span> RETURNS int8</div> |
| <div class="line"><a name="l00375"></a><span class="lineno"> 375</span> AS $$</div> |
| <div class="line"><a name="l00376"></a><span class="lineno"> 376</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00377"></a><span class="lineno"> 377</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00378"></a><span class="lineno"> 378</span> <span class="stringliteral"> return countmin.count(sketches64, val)</span></div> |
| <div class="line"><a name="l00379"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a323b932332f2db302469f14dc5fae369"> 379</a></span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00380"></a><span class="lineno"> 380</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00381"></a><span class="lineno"> 381</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00382"></a><span class="lineno"> 382</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00383"></a><span class="lineno"> 383</span> <span class="comment"> @brief <c>cmsketch_rangecount</c> is a scalar UDF to approximate the number</span></div> |
| <div class="line"><a name="l00384"></a><span class="lineno"> 384</span> <span class="comment"> of occurrences of values in the range <c>[lo,hi]</c> inclusive, given a</span></div> |
| <div class="line"><a name="l00385"></a><span class="lineno"> 385</span> <span class="comment"> cmsketch of a column. Takes the results</span></div> |
| <div class="line"><a name="l00386"></a><span class="lineno"> 386</span> <span class="comment"> of the <c>cmsketch</c> aggregate as its first argument, and the desired range</span></div> |
| <div class="line"><a name="l00387"></a><span class="lineno"> 387</span> <span class="comment"> boundaries as the second and third.</span></div> |
| <div class="line"><a name="l00388"></a><span class="lineno"> 388</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00389"></a><span class="lineno"> 389</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_rangecount(text, int8, int8) CASCADE;</div> |
| <div class="line"><a name="l00390"></a><span class="lineno"> 390</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_rangecount(sketches64 text, bot int8, top int8)</div> |
| <div class="line"><a name="l00391"></a><span class="lineno"> 391</span> RETURNS int8</div> |
| <div class="line"><a name="l00392"></a><span class="lineno"> 392</span> AS $$</div> |
| <div class="line"><a name="l00393"></a><span class="lineno"> 393</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00394"></a><span class="lineno"> 394</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00395"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a3498d2c778d1289154f61d34e84c609e"> 395</a></span> <span class="stringliteral"> return countmin.rangecount(sketches64, bot, top)</span></div> |
| <div class="line"><a name="l00396"></a><span class="lineno"> 396</span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00397"></a><span class="lineno"> 397</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00398"></a><span class="lineno"> 398</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00399"></a><span class="lineno"> 399</span> <span class="comment"> @brief <c>cmsketch_centile</c> is a scalar UDF to compute a centile value</span></div> |
| <div class="line"><a name="l00400"></a><span class="lineno"> 400</span> <span class="comment"> from a cmsketch. Takes the results of the <c>cmsketch</c> aggregate as its</span></div> |
| <div class="line"><a name="l00401"></a><span class="lineno"> 401</span> <span class="comment"> first argument, a number between 1 and 99 as the desired centile in the</span></div> |
| <div class="line"><a name="l00402"></a><span class="lineno"> 402</span> <span class="comment"> second, and the count of the column as the third. Produces a value from the</span></div> |
| <div class="line"><a name="l00403"></a><span class="lineno"> 403</span> <span class="comment"> sketched column that is approximately at the centile's position in sorted</span></div> |
| <div class="line"><a name="l00404"></a><span class="lineno"> 404</span> <span class="comment"> order.</span></div> |
| <div class="line"><a name="l00405"></a><span class="lineno"> 405</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00406"></a><span class="lineno"> 406</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_centile(text, int8, int8) CASCADE;</div> |
| <div class="line"><a name="l00407"></a><span class="lineno"> 407</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_centile(sketches64 text, centile int8, cnt int8)</div> |
| <div class="line"><a name="l00408"></a><span class="lineno"> 408</span> RETURNS int8</div> |
| <div class="line"><a name="l00409"></a><span class="lineno"> 409</span> AS $$</div> |
| <div class="line"><a name="l00410"></a><span class="lineno"> 410</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00411"></a><span class="lineno"> 411</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00412"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#aeff9e36cfb3338c4e405d4ac77d3968c"> 412</a></span> <span class="stringliteral"> return countmin.centile(sketches64, centile, cnt)</span></div> |
| <div class="line"><a name="l00413"></a><span class="lineno"> 413</span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00414"></a><span class="lineno"> 414</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00415"></a><span class="lineno"> 415</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00416"></a><span class="lineno"> 416</span> <span class="comment"> @brief <c>cmsketch_median</c> is a scalar UDF to compute a median value</span></div> |
| <div class="line"><a name="l00417"></a><span class="lineno"> 417</span> <span class="comment"> from a cmsketch. Takes the results of the <c>cmsketch</c> aggregate as its</span></div> |
| <div class="line"><a name="l00418"></a><span class="lineno"> 418</span> <span class="comment"> first argument, and the count as the second. Produces a value from the</span></div> |
| <div class="line"><a name="l00419"></a><span class="lineno"> 419</span> <span class="comment"> sketched column that is approximately at the halfway position in sorted</span></div> |
| <div class="line"><a name="l00420"></a><span class="lineno"> 420</span> <span class="comment"> order.</span></div> |
| <div class="line"><a name="l00421"></a><span class="lineno"> 421</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00422"></a><span class="lineno"> 422</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_median(text, int8) CASCADE;</div> |
| <div class="line"><a name="l00423"></a><span class="lineno"> 423</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_median(sketches64 text, cnt int8)</div> |
| <div class="line"><a name="l00424"></a><span class="lineno"> 424</span> RETURNS int8</div> |
| <div class="line"><a name="l00425"></a><span class="lineno"> 425</span> AS $$</div> |
| <div class="line"><a name="l00426"></a><span class="lineno"> 426</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00427"></a><span class="lineno"> 427</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00428"></a><span class="lineno"> 428</span> <span class="stringliteral"> return countmin.centile(sketches64, 50, cnt)</span></div> |
| <div class="line"><a name="l00429"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a2f2ab2fe3244515f5f73d49690e73b39"> 429</a></span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00430"></a><span class="lineno"> 430</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00431"></a><span class="lineno"> 431</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00432"></a><span class="lineno"> 432</span> <span class="comment"> \brief <c>cmsketch_width_histogram</c> is a scalar UDF that takes three aggregates of a column -- cmsketch, min and max-- as well as a number of buckets, and produces an n-bucket histogram for the column where each bucket has approximately the same width. The output is a text string containing triples {lo, hi, count} representing the buckets; counts are approximate.</span></div> |
| <div class="line"><a name="l00433"></a><span class="lineno"> 433</span> <span class="comment"> */</span></div> |
| <div class="line"><a name="l00434"></a><span class="lineno"> 434</span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_width_histogram(text, /*+ min */int8, /*+ max */int8, /*+ nbuckets */ int4) CASCADE;</div> |
| <div class="line"><a name="l00435"></a><span class="lineno"> 435</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_width_histogram(sketches64 text, themin int8, themax int8, nbuckets int4)</div> |
| <div class="line"><a name="l00436"></a><span class="lineno"> 436</span> RETURNS text</div> |
| <div class="line"><a name="l00437"></a><span class="lineno"> 437</span> AS $$</div> |
| <div class="line"><a name="l00438"></a><span class="lineno"> 438</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00439"></a><span class="lineno"> 439</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00440"></a><span class="lineno"> 440</span> <span class="stringliteral"> return countmin.width_histogram( sketches64, themin, themax, nbuckets)</span></div> |
| <div class="line"><a name="l00441"></a><span class="lineno"> 441</span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00442"></a><span class="lineno"> 442</span> <span class="stringliteral"></span><span class="comment"></span></div> |
| <div class="line"><a name="l00443"></a><span class="lineno"> 443</span> <span class="comment">/** @brief <c>cmsketch_depth_histogram</c> is a UDA that takes a cmsketch and a number of buckets n, and produces an n-bucket histogram for the column where each bucket has approximately the same count. The output is a text string containing triples {lo, hi, count} representing the buckets; counts are approximate. Note that an equi-depth histogram is equivalent to a spanning set of equi-spaced centiles.</span></div> |
| <div class="line"><a name="l00444"></a><span class="lineno"> 444</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00445"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a0ef6428fa7ba4b7f7b1f633e6f8003ea"> 445</a></span> DROP FUNCTION IF EXISTS MADLIB_SCHEMA.cmsketch_depth_histogram(text, /*+ nbuckets */ int4) CASCADE;</div> |
| <div class="line"><a name="l00446"></a><span class="lineno"> 446</span> CREATE FUNCTION MADLIB_SCHEMA.cmsketch_depth_histogram(sketches64 text, nbuckets int4)</div> |
| <div class="line"><a name="l00447"></a><span class="lineno"> 447</span> RETURNS text</div> |
| <div class="line"><a name="l00448"></a><span class="lineno"> 448</span> AS $$</div> |
| <div class="line"><a name="l00449"></a><span class="lineno"> 449</span>  PythonFunctionBodyOnly(`sketch', `countmin<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00450"></a><span class="lineno"> 450</span> <span class="stringliteral"> # schema_madlib comes from PythonFunctionBodyOnly</span></div> |
| <div class="line"><a name="l00451"></a><span class="lineno"> 451</span> <span class="stringliteral"> return countmin.depth_histogram(sketches64, nbuckets)</span></div> |
| <div class="line"><a name="l00452"></a><span class="lineno"> 452</span> <span class="stringliteral">$$ LANGUAGE plpythonu;</span></div> |
| <div class="line"><a name="l00453"></a><span class="lineno"> 453</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00454"></a><span class="lineno"> 454</span> <span class="stringliteral">-- MFV Sketch functions</span></div> |
| <div class="line"><a name="l00455"></a><span class="lineno"> 455</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00456"></a><span class="lineno"> 456</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__mfvsketch_trans(bytea, anyelement, int4) CASCADE;</span></div> |
| <div class="line"><a name="l00457"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a8482f62849adf40a2c7df78c23ea33a4"> 457</a></span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__mfvsketch_trans(bytea, anyelement, int4)</span></div> |
| <div class="line"><a name="l00458"></a><span class="lineno"> 458</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00459"></a><span class="lineno"> 459</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00460"></a><span class="lineno"> 460</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00461"></a><span class="lineno"> 461</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00462"></a><span class="lineno"> 462</span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__mfvsketch_final(bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00463"></a><span class="lineno"> 463</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__mfvsketch_final(bytea)</span></div> |
| <div class="line"><a name="l00464"></a><span class="lineno"> 464</span> <span class="stringliteral">RETURNS text[][]</span></div> |
| <div class="line"><a name="l00465"></a><span class="lineno"> 465</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00466"></a><span class="lineno"> 466</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00467"></a><span class="lineno"> 467</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00468"></a><span class="lineno"><a class="code" href="sketch_8sql__in.html#a9e6d30f20b724b96249cc4a0f67a279e"> 468</a></span> <span class="stringliteral">DROP FUNCTION IF EXISTS MADLIB_SCHEMA.__mfvsketch_merge(bytea, bytea) CASCADE;</span></div> |
| <div class="line"><a name="l00469"></a><span class="lineno"> 469</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__mfvsketch_merge(bytea, bytea)</span></div> |
| <div class="line"><a name="l00470"></a><span class="lineno"> 470</span> <span class="stringliteral">RETURNS bytea</span></div> |
| <div class="line"><a name="l00471"></a><span class="lineno"> 471</span> <span class="stringliteral">AS '</span>MODULE_PATHNAME<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00472"></a><span class="lineno"> 472</span> <span class="stringliteral">LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00473"></a><span class="lineno"> 473</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00474"></a><span class="lineno"> 474</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__sketch_rightmost_one(bytea, integer, integer)</span></div> |
| <div class="line"><a name="l00475"></a><span class="lineno"> 475</span> <span class="stringliteral">RETURNS integer AS '</span>MODULE_PATHNAME<span class="stringliteral">', '</span>sketch_rightmost_one<span class="stringliteral">' LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00476"></a><span class="lineno"> 476</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00477"></a><span class="lineno"> 477</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__sketch_leftmost_zero(bytea, integer, integer)</span></div> |
| <div class="line"><a name="l00478"></a><span class="lineno"> 478</span> <span class="stringliteral">RETURNS integer AS '</span>MODULE_PATHNAME<span class="stringliteral">', '</span>sketch_leftmost_zero<span class="stringliteral">' LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00479"></a><span class="lineno"> 479</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00480"></a><span class="lineno"> 480</span> <span class="stringliteral">CREATE FUNCTION MADLIB_SCHEMA.__sketch_array_set_bit_in_place(bytea, integer, integer, integer, integer)</span></div> |
| <div class="line"><a name="l00481"></a><span class="lineno"> 481</span> <span class="stringliteral">RETURNS bytea AS '</span>MODULE_PATHNAME<span class="stringliteral">', '</span>sketch_array_set_bit_in_place<span class="stringliteral">' LANGUAGE C STRICT;</span></div> |
| <div class="line"><a name="l00482"></a><span class="lineno"> 482</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00483"></a><span class="lineno"> 483</span> <span class="stringliteral">DROP AGGREGATE IF EXISTS MADLIB_SCHEMA.mfvsketch_top_histogram( anyelement, int4);</span><span class="comment"></span></div> |
| <div class="line"><a name="l00484"></a><span class="lineno"> 484</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00485"></a><span class="lineno"> 485</span> <span class="comment"> * @brief Produces an n-bucket histogram for a column where each bucket counts</span></div> |
| <div class="line"><a name="l00486"></a><span class="lineno"> 486</span> <span class="comment"> * one of the most frequent values in the column. The output is an array of</span></div> |
| <div class="line"><a name="l00487"></a><span class="lineno"> 487</span> <span class="comment"> * doubles {value, count} in descending order of frequency; counts are</span></div> |
| <div class="line"><a name="l00488"></a><span class="lineno"> 488</span> <span class="comment"> * approximated via CountMin sketches. Ties are handled arbitrarily.</span></div> |
| <div class="line"><a name="l00489"></a><span class="lineno"> 489</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00490"></a><span class="lineno"> 490</span> CREATE AGGREGATE MADLIB_SCHEMA.mfvsketch_top_histogram(/*+ column */ anyelement, /*+ number_of_buckets */ int4)</div> |
| <div class="line"><a name="l00491"></a><span class="lineno"> 491</span> (</div> |
| <div class="line"><a name="l00492"></a><span class="lineno"> 492</span>  sfunc = MADLIB_SCHEMA.__mfvsketch_trans,</div> |
| <div class="line"><a name="l00493"></a><span class="lineno"> 493</span>  stype = bytea,</div> |
| <div class="line"><a name="l00494"></a><span class="lineno"> 494</span>  finalfunc = MADLIB_SCHEMA.__mfvsketch_final,</div> |
| <div class="line"><a name="l00495"></a><span class="lineno"> 495</span>  initcond = '<span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00496"></a><span class="lineno"> 496</span> <span class="stringliteral">);</span></div> |
| <div class="line"><a name="l00497"></a><span class="lineno"> 497</span> <span class="stringliteral"></span></div> |
| <div class="line"><a name="l00498"></a><span class="lineno"> 498</span> <span class="stringliteral">DROP AGGREGATE IF EXISTS MADLIB_SCHEMA.mfvsketch_quick_histogram(anyelement, int4);</span><span class="comment"></span></div> |
| <div class="line"><a name="l00499"></a><span class="lineno"> 499</span> <span class="comment">/**</span></div> |
| <div class="line"><a name="l00500"></a><span class="lineno"> 500</span> <span class="comment"> * @brief On Postgres it works the same way as \ref mfvsketch_top_histogram but,</span></div> |
| <div class="line"><a name="l00501"></a><span class="lineno"> 501</span> <span class="comment"> * in Greenplum it does parallel aggregation to provide a "quick and dirty" answer.</span></div> |
| <div class="line"><a name="l00502"></a><span class="lineno"> 502</span> <span class="comment">*/</span></div> |
| <div class="line"><a name="l00503"></a><span class="lineno"> 503</span> CREATE AGGREGATE MADLIB_SCHEMA.mfvsketch_quick_histogram(/*+ column */ anyelement, /*+ number_of_buckets */ int4)</div> |
| <div class="line"><a name="l00504"></a><span class="lineno"> 504</span> (</div> |
| <div class="line"><a name="l00505"></a><span class="lineno"> 505</span>  sfunc = MADLIB_SCHEMA.__mfvsketch_trans,</div> |
| <div class="line"><a name="l00506"></a><span class="lineno"> 506</span>  stype = bytea,</div> |
| <div class="line"><a name="l00507"></a><span class="lineno"> 507</span>  finalfunc = MADLIB_SCHEMA.__mfvsketch_final,</div> |
| <div class="line"><a name="l00508"></a><span class="lineno"> 508</span>  m4_ifdef(`__GREENPLUM__', `prefunc = MADLIB_SCHEMA.__mfvsketch_merge,<span class="stringliteral">')</span></div> |
| <div class="line"><a name="l00509"></a><span class="lineno"> 509</span> <span class="stringliteral"> initcond = '</span><span class="stringliteral">'</span></div> |
| <div class="line"><a name="l00510"></a><span class="lineno"> 510</span> <span class="stringliteral">);</span></div> |
| </div><!-- fragment --></div><!-- contents --> |
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| <ul> |
| <li class="navelem"><a class="el" href="dir_704eb8350b43e1ca74c0f90ed1ba450e.html">methods</a></li><li class="navelem"><a class="el" href="dir_b0d8a62e5a4314de84ce58e7cd249850.html">sketch</a></li><li class="navelem"><a class="el" href="dir_60056874394c01e6c892c7492b3fbe27.html">src</a></li><li class="navelem"><a class="el" href="dir_c2d3987992538edb8f634d5f4e0fae80.html">pg_gp</a></li><li class="navelem"><a class="el" href="sketch_8sql__in.html">sketch.sql_in</a></li> |
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