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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> | |

<concept id="sum"> | |

<title>SUM Function</title> | |

<titlealts audience="PDF"><navtitle>SUM</navtitle></titlealts> | |

<prolog> | |

<metadata> | |

<data name="Category" value="Impala"/> | |

<data name="Category" value="SQL"/> | |

<data name="Category" value="Impala Functions"/> | |

<data name="Category" value="Analytic Functions"/> | |

<data name="Category" value="Aggregate Functions"/> | |

<data name="Category" value="Querying"/> | |

<data name="Category" value="Developers"/> | |

<data name="Category" value="Data Analysts"/> | |

</metadata> | |

</prolog> | |

<conbody> | |

<p> | |

<indexterm audience="hidden">sum() function</indexterm> | |

An aggregate function that returns the sum of a set of numbers. Its single argument can be numeric column, or | |

the numeric result of a function or expression applied to the column value. Rows with a <codeph>NULL</codeph> | |

value for the specified column are ignored. If the table is empty, or all the values supplied to | |

<codeph>MIN</codeph> are <codeph>NULL</codeph>, <codeph>SUM</codeph> returns <codeph>NULL</codeph>. | |

</p> | |

<p conref="../shared/impala_common.xml#common/syntax_blurb"/> | |

<codeblock>SUM([DISTINCT | ALL] <varname>expression</varname>) [OVER (<varname>analytic_clause</varname>)]</codeblock> | |

<p> | |

When the query contains a <codeph>GROUP BY</codeph> clause, returns one value for each combination of | |

grouping values. | |

</p> | |

<p> | |

<b>Return type:</b> <codeph>BIGINT</codeph> for integer arguments, <codeph>DOUBLE</codeph> for floating-point | |

arguments | |

</p> | |

<p conref="../shared/impala_common.xml#common/complex_types_blurb"/> | |

<p conref="../shared/impala_common.xml#common/complex_types_aggregation_explanation"/> | |

<p conref="../shared/impala_common.xml#common/complex_types_aggregation_example"/> | |

<p conref="../shared/impala_common.xml#common/example_blurb"/> | |

<p> | |

The following example shows how to use <codeph>SUM()</codeph> to compute the total for all the values in the | |

table, a subset of values, or the sum for each combination of values in the <codeph>GROUP BY</codeph> clause: | |

</p> | |

<codeblock>-- Total all the values for this column in the table. | |

select sum(c1) from t1; | |

-- Find the total for this column from a subset of the table. | |

select sum(c1) from t1 where month = 'January' and year = '2013'; | |

-- Find the total from a set of numeric function results. | |

select sum(length(s)) from t1; | |

-- Often used with functions that return predefined values to compute a score. | |

select sum(case when grade = 'A' then 1.0 when grade = 'B' then 0.75 else 0) as class_honors from test_scores; | |

-- Can also be used in combination with DISTINCT and/or GROUP BY. | |

-- Return more than one result. | |

select month, year, sum(purchase_price) from store_stats group by month, year; | |

-- Filter the input to eliminate duplicates before performing the calculation. | |

select sum(distinct x) from t1; | |

</codeblock> | |

<p rev="2.0.0"> | |

The following examples show how to use <codeph>SUM()</codeph> in an analytic context. They use a table | |

containing integers from 1 to 10. Notice how the <codeph>SUM()</codeph> is reported for each input value, as | |

opposed to the <codeph>GROUP BY</codeph> clause which condenses the result set. | |

<codeblock>select x, property, sum(x) <b>over (partition by property)</b> as sum from int_t where property in ('odd','even'); | |

+----+----------+-----+ | |

| x | property | sum | | |

+----+----------+-----+ | |

| 2 | even | 30 | | |

| 4 | even | 30 | | |

| 6 | even | 30 | | |

| 8 | even | 30 | | |

| 10 | even | 30 | | |

| 1 | odd | 25 | | |

| 3 | odd | 25 | | |

| 5 | odd | 25 | | |

| 7 | odd | 25 | | |

| 9 | odd | 25 | | |

+----+----------+-----+ | |

</codeblock> | |

Adding an <codeph>ORDER BY</codeph> clause lets you experiment with results that are cumulative or apply to a moving | |

set of rows (the <q>window</q>). The following examples use <codeph>SUM()</codeph> in an analytic context | |

(that is, with an <codeph>OVER()</codeph> clause) to produce a running total of all the even values, | |

then a running total of all the odd values. The basic <codeph>ORDER BY x</codeph> clause implicitly | |

activates a window clause of <codeph>RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW</codeph>, | |

which is effectively the same as <codeph>ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW</codeph>, | |

therefore all of these examples produce the same results: | |

<codeblock>select x, property, | |

sum(x) over (partition by property <b>order by x</b>) as 'cumulative total' | |

from int_t where property in ('odd','even'); | |

+----+----------+------------------+ | |

| x | property | cumulative total | | |

+----+----------+------------------+ | |

| 2 | even | 2 | | |

| 4 | even | 6 | | |

| 6 | even | 12 | | |

| 8 | even | 20 | | |

| 10 | even | 30 | | |

| 1 | odd | 1 | | |

| 3 | odd | 4 | | |

| 5 | odd | 9 | | |

| 7 | odd | 16 | | |

| 9 | odd | 25 | | |

+----+----------+------------------+ | |

select x, property, | |

sum(x) over | |

( | |

partition by property | |

<b>order by x</b> | |

<b>range between unbounded preceding and current row</b> | |

) as 'cumulative total' | |

from int_t where property in ('odd','even'); | |

+----+----------+------------------+ | |

| x | property | cumulative total | | |

+----+----------+------------------+ | |

| 2 | even | 2 | | |

| 4 | even | 6 | | |

| 6 | even | 12 | | |

| 8 | even | 20 | | |

| 10 | even | 30 | | |

| 1 | odd | 1 | | |

| 3 | odd | 4 | | |

| 5 | odd | 9 | | |

| 7 | odd | 16 | | |

| 9 | odd | 25 | | |

+----+----------+------------------+ | |

select x, property, | |

sum(x) over | |

( | |

partition by property | |

<b>order by x</b> | |

<b>rows between unbounded preceding and current row</b> | |

) as 'cumulative total' | |

from int_t where property in ('odd','even'); | |

+----+----------+------------------+ | |

| x | property | cumulative total | | |

+----+----------+------------------+ | |

| 2 | even | 2 | | |

| 4 | even | 6 | | |

| 6 | even | 12 | | |

| 8 | even | 20 | | |

| 10 | even | 30 | | |

| 1 | odd | 1 | | |

| 3 | odd | 4 | | |

| 5 | odd | 9 | | |

| 7 | odd | 16 | | |

| 9 | odd | 25 | | |

+----+----------+------------------+ | |

</codeblock> | |

Changing the direction of the <codeph>ORDER BY</codeph> clause causes the intermediate | |

results of the cumulative total to be calculated in a different order: | |

<codeblock>select sum(x) over (partition by property <b>order by x desc</b>) as 'cumulative total' | |

from int_t where property in ('odd','even'); | |

+----+----------+------------------+ | |

| x | property | cumulative total | | |

+----+----------+------------------+ | |

| 10 | even | 10 | | |

| 8 | even | 18 | | |

| 6 | even | 24 | | |

| 4 | even | 28 | | |

| 2 | even | 30 | | |

| 9 | odd | 9 | | |

| 7 | odd | 16 | | |

| 5 | odd | 21 | | |

| 3 | odd | 24 | | |

| 1 | odd | 25 | | |

+----+----------+------------------+ | |

</codeblock> | |

The following examples show how to construct a moving window, with a running total taking into account 1 row before | |

and 1 row after the current row, within the same partition (all the even values or all the odd values). | |

Because of a restriction in the Impala <codeph>RANGE</codeph> syntax, this type of | |

moving window is possible with the <codeph>ROWS BETWEEN</codeph> clause but not the <codeph>RANGE BETWEEN</codeph> | |

clause: | |

<codeblock>select x, property, | |

sum(x) over | |

( | |

partition by property | |

<b>order by x</b> | |

<b>rows between 1 preceding and 1 following</b> | |

) as 'moving total' | |

from int_t where property in ('odd','even'); | |

+----+----------+--------------+ | |

| x | property | moving total | | |

+----+----------+--------------+ | |

| 2 | even | 6 | | |

| 4 | even | 12 | | |

| 6 | even | 18 | | |

| 8 | even | 24 | | |

| 10 | even | 18 | | |

| 1 | odd | 4 | | |

| 3 | odd | 9 | | |

| 5 | odd | 15 | | |

| 7 | odd | 21 | | |

| 9 | odd | 16 | | |

+----+----------+--------------+ | |

-- Doesn't work because of syntax restriction on RANGE clause. | |

select x, property, | |

sum(x) over | |

( | |

partition by property | |

<b>order by x</b> | |

<b>range between 1 preceding and 1 following</b> | |

) as 'moving total' | |

from int_t where property in ('odd','even'); | |

ERROR: AnalysisException: RANGE is only supported with both the lower and upper bounds UNBOUNDED or one UNBOUNDED and the other CURRENT ROW. | |

</codeblock> | |

</p> | |

<p conref="../shared/impala_common.xml#common/restrictions_blurb"/> | |

<!-- This conref appears under SUM(), AVG(), FLOAT, and DOUBLE topics. --> | |

<p conref="../shared/impala_common.xml#common/sum_double"/> | |

<p conref="../shared/impala_common.xml#common/related_info"/> | |

<p> | |

<xref href="impala_analytic_functions.xml#analytic_functions"/> | |

</p> | |

</conbody> | |

</concept> |