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| <div class="title">hyperloglog-uda.cc</div> </div> |
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| <a href="hyperloglog-uda_8cc.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">// Copyright 2012 Cloudera Inc.</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">// Licensed under the Apache License, Version 2.0 (the "License");</span></div> |
| <div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">// you may not use this file except in compliance with the License.</span></div> |
| <div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">// You may obtain a copy of the License at</span></div> |
| <div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment">//</span></div> |
| <div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment">// http://www.apache.org/licenses/LICENSE-2.0</span></div> |
| <div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment">//</span></div> |
| <div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment">// Unless required by applicable law or agreed to in writing, software</span></div> |
| <div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment">// distributed under the License is distributed on an "AS IS" BASIS,</span></div> |
| <div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment">// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span></div> |
| <div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment">// See the License for the specific language governing permissions and</span></div> |
| <div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment">// limitations under the License.</span></div> |
| <div class="line"><a name="l00014"></a><span class="lineno"> 14</span> </div> |
| <div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="preprocessor">#include <assert.h></span></div> |
| <div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="preprocessor">#include <math.h></span></div> |
| <div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="preprocessor">#include <algorithm></span></div> |
| <div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="preprocessor">#include <sstream></span></div> |
| <div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="preprocessor">#include <iostream></span></div> |
| <div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="preprocessor">#include "<a class="code" href="udf_8h.html">udf/udf.h</a>"</span></div> |
| <div class="line"><a name="l00021"></a><span class="lineno"> 21</span> </div> |
| <div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="preprocessor">#include "<a class="code" href="names_8h.html">common/names.h</a>"</span></div> |
| <div class="line"><a name="l00023"></a><span class="lineno"> 23</span> </div> |
| <div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="keyword">using</span> std::max;</div> |
| <div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="keyword">using namespace </span>impala_udf;</div> |
| <div class="line"><a name="l00026"></a><span class="lineno"> 26</span> </div> |
| <div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment">// This sample UDA implements the hyperloglog distinct estimate aggregate</span></div> |
| <div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment">// function.</span></div> |
| <div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">// See these papers for more details.</span></div> |
| <div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="comment">// 1) Hyperloglog: The analysis of a near-optimal cardinality estimation algorithm (2007)</span></div> |
| <div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="comment">// 2) HyperLogLog in Practice</span></div> |
| <div class="line"><a name="l00032"></a><span class="lineno"> 32</span> </div> |
| <div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="comment">// Precision taken from the paper. Doesn't seem to matter very much when between [6,12]</span></div> |
| <div class="line"><a name="l00034"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4"> 34</a></span> <span class="keyword">const</span> <span class="keywordtype">int</span> <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a> = 10;</div> |
| <div class="line"><a name="l00035"></a><span class="lineno"> 35</span> </div> |
| <div class="line"><a name="l00036"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#ad0ff2d99278dfa01c8ed24dbf545ae32"> 36</a></span> <span class="keywordtype">void</span> <a class="code" href="hyperloglog-uda_8cc.html#ad0ff2d99278dfa01c8ed24dbf545ae32">HllInit</a>(<a class="code" href="classimpala__udf_1_1FunctionContext.html">FunctionContext</a>* ctx, <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>* dst) {</div> |
| <div class="line"><a name="l00037"></a><span class="lineno"> 37</span>  <span class="keywordtype">int</span> str_len = pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>);</div> |
| <div class="line"><a name="l00038"></a><span class="lineno"> 38</span>  dst-><a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a> = <span class="keyword">false</span>;</div> |
| <div class="line"><a name="l00039"></a><span class="lineno"> 39</span>  dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a> = ctx-><a class="code" href="classimpala__udf_1_1FunctionContext.html#a24a7e63aa708e54ea3c8c9572a00ede2">Allocate</a>(str_len);</div> |
| <div class="line"><a name="l00040"></a><span class="lineno"> 40</span>  dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a> = str_len;</div> |
| <div class="line"><a name="l00041"></a><span class="lineno"> 41</span>  memset(dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>, 0, str_len);</div> |
| <div class="line"><a name="l00042"></a><span class="lineno"> 42</span> }</div> |
| <div class="line"><a name="l00043"></a><span class="lineno"> 43</span> </div> |
| <div class="line"><a name="l00044"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#a4eb84a6b1e8899cdcc9814951f27a4ae"> 44</a></span> <span class="keyword">static</span> <span class="keyword">const</span> <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="hyperloglog-uda_8cc.html#a4eb84a6b1e8899cdcc9814951f27a4ae">FNV64_PRIME</a> = 1099511628211UL;</div> |
| <div class="line"><a name="l00045"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#a6a1acecdeef9496105781d8486a7193b"> 45</a></span> <span class="keyword">static</span> <span class="keyword">const</span> <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="hyperloglog-uda_8cc.html#a6a1acecdeef9496105781d8486a7193b">FNV64_SEED</a> = 14695981039346656037UL;</div> |
| <div class="line"><a name="l00046"></a><span class="lineno"> 46</span> </div> |
| <div class="line"><a name="l00047"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#a534edfc687e03f750ff4332612b6142d"> 47</a></span> <span class="keyword">static</span> <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="hyperloglog-uda_8cc.html#a534edfc687e03f750ff4332612b6142d">FnvHash</a>(<span class="keyword">const</span> <span class="keywordtype">void</span>* data, int32_t bytes, <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="namespaceimpala.html#a50b59c9628eedf49aa82643ce601967d">hash</a>) {</div> |
| <div class="line"><a name="l00048"></a><span class="lineno"> 48</span>  <span class="keyword">const</span> uint8_t* ptr = <span class="keyword">reinterpret_cast<</span><span class="keyword">const </span>uint8_t*<span class="keyword">></span>(data);</div> |
| <div class="line"><a name="l00049"></a><span class="lineno"> 49</span>  <span class="keywordflow">while</span> (bytes--) {</div> |
| <div class="line"><a name="l00050"></a><span class="lineno"> 50</span>  hash = (*ptr ^ <a class="code" href="namespaceimpala.html#a50b59c9628eedf49aa82643ce601967d">hash</a>) * <a class="code" href="hyperloglog-uda_8cc.html#a4eb84a6b1e8899cdcc9814951f27a4ae">FNV64_PRIME</a>;</div> |
| <div class="line"><a name="l00051"></a><span class="lineno"> 51</span>  ++ptr;</div> |
| <div class="line"><a name="l00052"></a><span class="lineno"> 52</span>  }</div> |
| <div class="line"><a name="l00053"></a><span class="lineno"> 53</span>  <span class="keywordflow">return</span> <a class="code" href="namespaceimpala.html#a50b59c9628eedf49aa82643ce601967d">hash</a>;</div> |
| <div class="line"><a name="l00054"></a><span class="lineno"> 54</span> }</div> |
| <div class="line"><a name="l00055"></a><span class="lineno"> 55</span> </div> |
| <div class="line"><a name="l00056"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#acad87215d091845338b21a13538ef952"> 56</a></span> <span class="keyword">static</span> <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="hyperloglog-uda_8cc.html#acad87215d091845338b21a13538ef952">Hash</a>(<span class="keyword">const</span> <a class="code" href="structimpala__udf_1_1IntVal.html">IntVal</a>& v) {</div> |
| <div class="line"><a name="l00057"></a><span class="lineno"> 57</span>  <span class="keywordflow">return</span> <a class="code" href="hyperloglog-uda_8cc.html#a534edfc687e03f750ff4332612b6142d">FnvHash</a>(&v.<a class="code" href="structimpala__udf_1_1IntVal.html#a48ca54ea2f6824162d8fbdc64d5c3771">val</a>, <span class="keyword">sizeof</span>(int32_t), <a class="code" href="hyperloglog-uda_8cc.html#a6a1acecdeef9496105781d8486a7193b">FNV64_SEED</a>);</div> |
| <div class="line"><a name="l00058"></a><span class="lineno"> 58</span> }</div> |
| <div class="line"><a name="l00059"></a><span class="lineno"> 59</span> </div> |
| <div class="line"><a name="l00060"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#a944efa60517e036f931688cd021d799f"> 60</a></span> <span class="keywordtype">void</span> <a class="code" href="hyperloglog-uda_8cc.html#a944efa60517e036f931688cd021d799f">HllUpdate</a>(<a class="code" href="classimpala__udf_1_1FunctionContext.html">FunctionContext</a>* ctx, <span class="keyword">const</span> <a class="code" href="structimpala__udf_1_1IntVal.html">IntVal</a>& src, <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>* dst) {</div> |
| <div class="line"><a name="l00061"></a><span class="lineno"> 61</span>  <span class="keywordflow">if</span> (src.<a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>) <span class="keywordflow">return</span>;</div> |
| <div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  assert(dst != NULL);</div> |
| <div class="line"><a name="l00063"></a><span class="lineno"> 63</span>  assert(!dst-><a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>);</div> |
| <div class="line"><a name="l00064"></a><span class="lineno"> 64</span>  assert(dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a> == pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>));</div> |
| <div class="line"><a name="l00065"></a><span class="lineno"> 65</span>  <a class="code" href="classuint64__t.html">uint64_t</a> <a class="code" href="namespaceimpala.html#ac0255e5845537ea9f1d3938ecb19d02c">hash_value</a> = <a class="code" href="hyperloglog-uda_8cc.html#acad87215d091845338b21a13538ef952">Hash</a>(src);</div> |
| <div class="line"><a name="l00066"></a><span class="lineno"> 66</span>  <span class="keywordflow">if</span> (hash_value != 0) {</div> |
| <div class="line"><a name="l00067"></a><span class="lineno"> 67</span>  <span class="comment">// Use the lower bits to index into the number of streams and then</span></div> |
| <div class="line"><a name="l00068"></a><span class="lineno"> 68</span>  <span class="comment">// find the first 1 bit after the index bits.</span></div> |
| <div class="line"><a name="l00069"></a><span class="lineno"> 69</span>  <span class="keywordtype">int</span> <a class="code" href="namespacegen__ir__descriptions.html#a0d6572990c8dd576a55a21ff11d6deb7">idx</a> = hash_value % dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a>;</div> |
| <div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  uint8_t first_one_bit = __builtin_ctzl(hash_value >> <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>) + 1;</div> |
| <div class="line"><a name="l00071"></a><span class="lineno"> 71</span>  dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[<a class="code" href="namespacegen__ir__descriptions.html#a0d6572990c8dd576a55a21ff11d6deb7">idx</a>] = ::max(dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[idx], first_one_bit);</div> |
| <div class="line"><a name="l00072"></a><span class="lineno"> 72</span>  }</div> |
| <div class="line"><a name="l00073"></a><span class="lineno"> 73</span> }</div> |
| <div class="line"><a name="l00074"></a><span class="lineno"> 74</span> </div> |
| <div class="line"><a name="l00075"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#ae112622a66d49befd4925837a7435f99"> 75</a></span> <span class="keywordtype">void</span> <a class="code" href="hyperloglog-uda_8cc.html#ae112622a66d49befd4925837a7435f99">HllMerge</a>(<a class="code" href="classimpala__udf_1_1FunctionContext.html">FunctionContext</a>* ctx, <span class="keyword">const</span> <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>& src, <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>* dst) {</div> |
| <div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  assert(dst != NULL);</div> |
| <div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  assert(!dst-><a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>);</div> |
| <div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  assert(!src.<a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>);</div> |
| <div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  assert(dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a> == pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>));</div> |
| <div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  assert(src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a> == pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>));</div> |
| <div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a>; ++i) {</div> |
| <div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[i] = ::max(dst-><a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[i], src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[i]);</div> |
| <div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  }</div> |
| <div class="line"><a name="l00084"></a><span class="lineno"> 84</span> }</div> |
| <div class="line"><a name="l00085"></a><span class="lineno"> 85</span> </div> |
| <div class="line"><a name="l00086"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#ab2ea415edbb6f87e039464e4b9fbc27b"> 86</a></span> <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a> <a class="code" href="hyperloglog-uda_8cc.html#ab2ea415edbb6f87e039464e4b9fbc27b">HllSerialize</a>(<a class="code" href="classimpala__udf_1_1FunctionContext.html">FunctionContext</a>* ctx, <span class="keyword">const</span> <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>& src) {</div> |
| <div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  <span class="keywordflow">if</span> (src.<a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>) <span class="keywordflow">return</span> src;</div> |
| <div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a> result(ctx, src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a>);</div> |
| <div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  memcpy(result.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>, src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>, src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a>);</div> |
| <div class="line"><a name="l00090"></a><span class="lineno"> 90</span>  ctx-><a class="code" href="classimpala__udf_1_1FunctionContext.html#a14904de2d63cac14b1a1ef09b0653a14">Free</a>(src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>);</div> |
| <div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  <span class="keywordflow">return</span> result;</div> |
| <div class="line"><a name="l00092"></a><span class="lineno"> 92</span> }</div> |
| <div class="line"><a name="l00093"></a><span class="lineno"> 93</span> </div> |
| <div class="line"><a name="l00094"></a><span class="lineno"><a class="line" href="hyperloglog-uda_8cc.html#abc438f731c28e8d9ab7264b3d915d403"> 94</a></span> <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a> <a class="code" href="hyperloglog-uda_8cc.html#abc438f731c28e8d9ab7264b3d915d403">HllFinalize</a>(<a class="code" href="classimpala__udf_1_1FunctionContext.html">FunctionContext</a>* ctx, <span class="keyword">const</span> <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a>& src) {</div> |
| <div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  assert(!src.<a class="code" href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">is_null</a>);</div> |
| <div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  assert(src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a> == pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>));</div> |
| <div class="line"><a name="l00097"></a><span class="lineno"> 97</span> </div> |
| <div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  <span class="keyword">const</span> <span class="keywordtype">int</span> num_streams = pow(2, <a class="code" href="hyperloglog-uda_8cc.html#a9daf82a707210a5b0ea86aa1ac139dc4">HLL_PRECISION</a>);</div> |
| <div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  <span class="comment">// Empirical constants for the algorithm.</span></div> |
| <div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  <span class="keywordtype">float</span> alpha = 0;</div> |
| <div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  <span class="keywordflow">if</span> (num_streams == 16) {</div> |
| <div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  alpha = 0.673f;</div> |
| <div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (num_streams == 32) {</div> |
| <div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  alpha = 0.697f;</div> |
| <div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  } <span class="keywordflow">else</span> <span class="keywordflow">if</span> (num_streams == 64) {</div> |
| <div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  alpha = 0.709f;</div> |
| <div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  } <span class="keywordflow">else</span> {</div> |
| <div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  alpha = 0.7213f / (1 + 1.079f / num_streams);</div> |
| <div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  }</div> |
| <div class="line"><a name="l00110"></a><span class="lineno"> 110</span> </div> |
| <div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="keywordtype">float</span> harmonic_mean = 0;</div> |
| <div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  <span class="keywordtype">int</span> num_zero_registers = 0;</div> |
| <div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < src.<a class="code" href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">len</a>; ++i) {</div> |
| <div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  harmonic_mean += powf(2.0f, -src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[i]);</div> |
| <div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  <span class="keywordflow">if</span> (src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>[i] == 0) ++num_zero_registers;</div> |
| <div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  }</div> |
| <div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  harmonic_mean = 1.0f / harmonic_mean;</div> |
| <div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  int64_t estimate = alpha * num_streams * num_streams * harmonic_mean;</div> |
| <div class="line"><a name="l00119"></a><span class="lineno"> 119</span> </div> |
| <div class="line"><a name="l00120"></a><span class="lineno"> 120</span>  <span class="keywordflow">if</span> (num_zero_registers != 0) {</div> |
| <div class="line"><a name="l00121"></a><span class="lineno"> 121</span>  <span class="comment">// Estimated cardinality is too low. Hll is too inaccurate here, instead use</span></div> |
| <div class="line"><a name="l00122"></a><span class="lineno"> 122</span>  <span class="comment">// linear counting.</span></div> |
| <div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  estimate = num_streams * log(static_cast<float>(num_streams) / num_zero_registers);</div> |
| <div class="line"><a name="l00124"></a><span class="lineno"> 124</span>  }</div> |
| <div class="line"><a name="l00125"></a><span class="lineno"> 125</span> </div> |
| <div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  <span class="comment">// Output the estimate as ascii string</span></div> |
| <div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  stringstream out;</div> |
| <div class="line"><a name="l00128"></a><span class="lineno"> 128</span>  out << estimate;</div> |
| <div class="line"><a name="l00129"></a><span class="lineno"> 129</span>  <span class="keywordtype">string</span> out_str = out.str();</div> |
| <div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  <a class="code" href="structimpala__udf_1_1StringVal.html">StringVal</a> result_str(ctx, out_str.size());</div> |
| <div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  memcpy(result_str.ptr, out_str.c_str(), result_str.len);</div> |
| <div class="line"><a name="l00132"></a><span class="lineno"> 132</span>  ctx-><a class="code" href="classimpala__udf_1_1FunctionContext.html#a14904de2d63cac14b1a1ef09b0653a14">Free</a>(src.<a class="code" href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">ptr</a>);</div> |
| <div class="line"><a name="l00133"></a><span class="lineno"> 133</span>  <span class="keywordflow">return</span> result_str;</div> |
| <div class="line"><a name="l00134"></a><span class="lineno"> 134</span> }</div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_ae112622a66d49befd4925837a7435f99"><div class="ttname"><a href="hyperloglog-uda_8cc.html#ae112622a66d49befd4925837a7435f99">HllMerge</a></div><div class="ttdeci">void HllMerge(FunctionContext *ctx, const StringVal &src, StringVal *dst)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00075">hyperloglog-uda.cc:75</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_abc438f731c28e8d9ab7264b3d915d403"><div class="ttname"><a href="hyperloglog-uda_8cc.html#abc438f731c28e8d9ab7264b3d915d403">HllFinalize</a></div><div class="ttdeci">StringVal HllFinalize(FunctionContext *ctx, const StringVal &src)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00094">hyperloglog-uda.cc:94</a></div></div> |
| <div class="ttc" id="namespaceimpala_html_a50b59c9628eedf49aa82643ce601967d"><div class="ttname"><a href="namespaceimpala.html#a50b59c9628eedf49aa82643ce601967d">impala::hash</a></div><div class="ttdeci">const StringSearch UrlParser::hash_search & hash</div><div class="ttdef"><b>Definition:</b> <a href="url-parser_8cc_source.html#l00041">url-parser.cc:41</a></div></div> |
| <div class="ttc" id="structimpala__udf_1_1IntVal_html_a48ca54ea2f6824162d8fbdc64d5c3771"><div class="ttname"><a href="structimpala__udf_1_1IntVal.html#a48ca54ea2f6824162d8fbdc64d5c3771">impala_udf::IntVal::val</a></div><div class="ttdeci">int32_t val</div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00421">udf.h:421</a></div></div> |
| <div class="ttc" id="udf_8h_html"><div class="ttname"><a href="udf_8h.html">udf.h</a></div></div> |
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| <div class="ttc" id="structimpala__udf_1_1StringVal_html_a1152442079d2471ec396076f37bf6c35"><div class="ttname"><a href="structimpala__udf_1_1StringVal.html#a1152442079d2471ec396076f37bf6c35">impala_udf::StringVal::ptr</a></div><div class="ttdeci">uint8_t * ptr</div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00523">udf.h:523</a></div></div> |
| <div class="ttc" id="namespaceimpala_html_ac0255e5845537ea9f1d3938ecb19d02c"><div class="ttname"><a href="namespaceimpala.html#ac0255e5845537ea9f1d3938ecb19d02c">impala::hash_value</a></div><div class="ttdeci">std::size_t hash_value(const Decimal4Value &v)</div><div class="ttdoc">This function must be called 'hash_value' to be picked up by boost. </div><div class="ttdef"><b>Definition:</b> <a href="decimal-value_8h_source.html#l00397">decimal-value.h:397</a></div></div> |
| <div class="ttc" id="classimpala__udf_1_1FunctionContext_html"><div class="ttname"><a href="classimpala__udf_1_1FunctionContext.html">impala_udf::FunctionContext</a></div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00047">udf.h:47</a></div></div> |
| <div class="ttc" id="structimpala__udf_1_1AnyVal_html_aded62c6b250c62814c94271856b06cbe"><div class="ttname"><a href="structimpala__udf_1_1AnyVal.html#aded62c6b250c62814c94271856b06cbe">impala_udf::AnyVal::is_null</a></div><div class="ttdeci">bool is_null</div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00359">udf.h:359</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_a534edfc687e03f750ff4332612b6142d"><div class="ttname"><a href="hyperloglog-uda_8cc.html#a534edfc687e03f750ff4332612b6142d">FnvHash</a></div><div class="ttdeci">static uint64_t FnvHash(const void *data, int32_t bytes, uint64_t hash)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00047">hyperloglog-uda.cc:47</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_ad0ff2d99278dfa01c8ed24dbf545ae32"><div class="ttname"><a href="hyperloglog-uda_8cc.html#ad0ff2d99278dfa01c8ed24dbf545ae32">HllInit</a></div><div class="ttdeci">void HllInit(FunctionContext *ctx, StringVal *dst)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00036">hyperloglog-uda.cc:36</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_a944efa60517e036f931688cd021d799f"><div class="ttname"><a href="hyperloglog-uda_8cc.html#a944efa60517e036f931688cd021d799f">HllUpdate</a></div><div class="ttdeci">void HllUpdate(FunctionContext *ctx, const IntVal &src, StringVal *dst)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00060">hyperloglog-uda.cc:60</a></div></div> |
| <div class="ttc" id="classuint64__t_html"><div class="ttname"><a href="classuint64__t.html">uint64_t</a></div></div> |
| <div class="ttc" id="classimpala__udf_1_1FunctionContext_html_a14904de2d63cac14b1a1ef09b0653a14"><div class="ttname"><a href="classimpala__udf_1_1FunctionContext.html#a14904de2d63cac14b1a1ef09b0653a14">impala_udf::FunctionContext::Free</a></div><div class="ttdeci">void Free(uint8_t *buffer)</div><div class="ttdoc">Frees a buffer returned from Allocate() or Reallocate() </div><div class="ttdef"><b>Definition:</b> <a href="udf_8cc_source.html#l00291">udf.cc:291</a></div></div> |
| <div class="ttc" id="structimpala__udf_1_1StringVal_html"><div class="ttname"><a href="structimpala__udf_1_1StringVal.html">impala_udf::StringVal</a></div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00521">udf.h:521</a></div></div> |
| <div class="ttc" id="structimpala__udf_1_1IntVal_html"><div class="ttname"><a href="structimpala__udf_1_1IntVal.html">impala_udf::IntVal</a></div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00420">udf.h:420</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_acad87215d091845338b21a13538ef952"><div class="ttname"><a href="hyperloglog-uda_8cc.html#acad87215d091845338b21a13538ef952">Hash</a></div><div class="ttdeci">static uint64_t Hash(const IntVal &v)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00056">hyperloglog-uda.cc:56</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_a4eb84a6b1e8899cdcc9814951f27a4ae"><div class="ttname"><a href="hyperloglog-uda_8cc.html#a4eb84a6b1e8899cdcc9814951f27a4ae">FNV64_PRIME</a></div><div class="ttdeci">static const uint64_t FNV64_PRIME</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00044">hyperloglog-uda.cc:44</a></div></div> |
| <div class="ttc" id="classimpala__udf_1_1FunctionContext_html_a24a7e63aa708e54ea3c8c9572a00ede2"><div class="ttname"><a href="classimpala__udf_1_1FunctionContext.html#a24a7e63aa708e54ea3c8c9572a00ede2">impala_udf::FunctionContext::Allocate</a></div><div class="ttdeci">uint8_t * Allocate(int byte_size)</div><div class="ttdef"><b>Definition:</b> <a href="udf_8cc_source.html#l00262">udf.cc:262</a></div></div> |
| <div class="ttc" id="names_8h_html"><div class="ttname"><a href="names_8h.html">names.h</a></div></div> |
| <div class="ttc" id="namespacegen__ir__descriptions_html_a0d6572990c8dd576a55a21ff11d6deb7"><div class="ttname"><a href="namespacegen__ir__descriptions.html#a0d6572990c8dd576a55a21ff11d6deb7">gen_ir_descriptions.idx</a></div><div class="ttdeci">int idx</div><div class="ttdef"><b>Definition:</b> <a href="gen__ir__descriptions_8py_source.html#l00215">gen_ir_descriptions.py:215</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_ab2ea415edbb6f87e039464e4b9fbc27b"><div class="ttname"><a href="hyperloglog-uda_8cc.html#ab2ea415edbb6f87e039464e4b9fbc27b">HllSerialize</a></div><div class="ttdeci">StringVal HllSerialize(FunctionContext *ctx, const StringVal &src)</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00086">hyperloglog-uda.cc:86</a></div></div> |
| <div class="ttc" id="hyperloglog-uda_8cc_html_a6a1acecdeef9496105781d8486a7193b"><div class="ttname"><a href="hyperloglog-uda_8cc.html#a6a1acecdeef9496105781d8486a7193b">FNV64_SEED</a></div><div class="ttdeci">static const uint64_t FNV64_SEED</div><div class="ttdef"><b>Definition:</b> <a href="hyperloglog-uda_8cc_source.html#l00045">hyperloglog-uda.cc:45</a></div></div> |
| <div class="ttc" id="structimpala__udf_1_1StringVal_html_a72a872d5acebca872db6bd37eb4ae184"><div class="ttname"><a href="structimpala__udf_1_1StringVal.html#a72a872d5acebca872db6bd37eb4ae184">impala_udf::StringVal::len</a></div><div class="ttdeci">int len</div><div class="ttdef"><b>Definition:</b> <a href="udf_8h_source.html#l00522">udf.h:522</a></div></div> |
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