GitHub user heary-cao reopened a pull request:
https://github.com/apache/spark/pull/18918
[SPARK-21707][SQL]Improvement a special case for non-deterministic filters
in optimizer
## What changes were proposed in this pull request?
Currently, Did a lot of special handling for non-deterministic projects and
filters in optimizer. but not good enough. this patch add a new special case
for non-deterministic filters. Deal with that we only need to read user needs
fields for non-deterministic filters in optimizer.
For example, the condition of filters is nondeterministic. e.g:contains
nondeterministic function(rand function), HiveTableScans optimizer generated:
```
HiveTableScans plan:Aggregate [k#2L], [k#2L, k#2L, sum(cast(id#1 as
bigint)) AS sum(id)#395L]
+- Project [d004#205 AS id#1, CEIL(c010#214) AS k#2L]
+- Filter ((isnotnull(d004#205) && (rand(-4530215890880734772) <= 0.5))
&& NOT (cast(cast(d004#205 as decimal(10,0)) as decimal(11,1)) = 0.0))
+- MetastoreRelation XXX_database, XXX_table
HiveTableScans plan:Project [d004#205 AS id#1, CEIL(c010#214) AS k#2L]
+- Filter ((isnotnull(d004#205) && (rand(-4530215890880734772) <= 0.5)) &&
NOT (cast(cast(d004#205 as decimal(10,0)) as decimal(11,1)) = 0.0))
+- MetastoreRelation XXX_database, XXX_table
HiveTableScans plan:Filter ((isnotnull(d004#205) &&
(rand(-4530215890880734772) <= 0.5)) && NOT (cast(cast(d004#205 as
decimal(10,0)) as decimal(11,1)) = 0.0))
+- MetastoreRelation XXX_database, XXX_table
HiveTableScans plan:MetastoreRelation XXX_database, XXX_table
HiveTableScans result plan:HiveTableScan [c030#204L, d004#205, d005#206,
d025#207, c002#208, d023#209, d024#210, c005#211L, c008#212, c009#213,
c010#214, d021#215, d022#216, c017#217, c018#218, c019#219, c020#220, c021#221,
c022#222, c023#223, c024#224, c025#225, c026#226, c027#227, ... 169 more
fields], MetastoreRelation XXX_database, XXX_table
```
so HiveTableScan will read all the fields from table. but we only need to
âd004â and 'c010' . it will affect the performance of task.
## How was this patch tested?
Should be covered existing test cases and add new test cases.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/heary-cao/spark filters_non_deterministic
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18918.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #18918
----
commit 97a32709f40c573bada4c46df0d00aad14425ee2
Author: caoxuewen <[email protected]>
Date: 2017-08-11T09:56:55Z
Improvement a special case for non-deterministic filters in optimizer
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