mirror of
https://github.com/apache/impala.git
synced 2025-12-19 09:58:28 -05:00
8377b9949c
For this change to land in master, the audience="hidden" code review needs to be completed first. Otherwise, the doc build would still work but the audience="hidden" content would be visible rather than hidden as desired. Some work happening in parallel might introduce additional instances of audience="Cloudera". I suggest addressing those in a followup CR so this global change can land quickly. Since the changes apply across so many different files, but are so narrow in scope, I suggest that the way to validate (check that no extraneous changes were introduced accidentally) is to diff just the changed lines: git diff -U0 HEAD^ HEAD In patch set 2, I updated other topics marked audience="Cloudera" by CRs that were pushed in the meantime. Change-Id: Ic93d89da77e1f51bbf548a522d98d0c4e2fb31c8 Reviewed-on: http://gerrit.cloudera.org:8080/5613 Reviewed-by: John Russell <jrussell@cloudera.com> Tested-by: Impala Public Jenkins
258 lines
10 KiB
XML
258 lines
10 KiB
XML
<?xml version="1.0" encoding="UTF-8"?><!--
|
|
Licensed to the Apache Software Foundation (ASF) under one
|
|
or more contributor license agreements. See the NOTICE file
|
|
distributed with this work for additional information
|
|
regarding copyright ownership. The ASF licenses this file
|
|
to you under the Apache License, Version 2.0 (the
|
|
"License"); you may not use this file except in compliance
|
|
with the License. You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing,
|
|
software distributed under the License is distributed on an
|
|
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
|
|
KIND, either express or implied. See the License for the
|
|
specific language governing permissions and limitations
|
|
under the License.
|
|
-->
|
|
<!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>
|