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release-2.1: distsql: eagerly evaluate constant expressions #31091

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merged 1 commit into from Oct 8, 2018

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@jordanlewis jordanlewis

@cockroachdb/sql-rest-prs sql-rest-prs

@cockroachdb/sql-execution-prs sql-execution-prs

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@solongordon @cockroach-teamcity @jordanlewis
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solongordon commented Oct 8, 2018

Backport 1/1 commits from #30216.

/cc @cockroachdb/release

exprHelper now normalizes its expression upon initialization. This
causes constant subexpressions to be evaluated up front, rather than re-
evaluating them every time eval or evalFilter is called, and thus
avoids a hefty per-row cost for expensive expressions. For example, the
SELECT query in the example below now returns in ~100ms rather than
~10s.

CREATE TABLE t (x int[]);
INSERT INTO t SELECT array[x] FROM generate_series(1, 10000) AS x;
SELECT * FROM t WHERE x = (SELECT array_agg(generate_series(1,10000)));

This also uncovered a bug in the normalizer where NOT IN () returned
false rather than true.

Fixes #30167

Release note: None
@solongordon
distsql: eagerly evaluate constant expressions 
exprHelper now evaluates constant subexpressions upon initialization,
rather than re-evaluating them every time `eval` or `evalFilter` is
called, and thus avoids a hefty per-row cost for expensive expressions.
For example, the SELECT query in the example below now returns in ~30ms
rather than ~10s.

```
CREATE TABLE t (x int[]);
INSERT INTO t SELECT array[x] FROM generate_series(1, 10000) AS x;
SELECT * FROM t WHERE x = (SELECT array_agg(generate_series(1,10000)));
```

Fixes #30167

Release note: None
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@solongordon solongordon requested a review from jordanlewis Oct 8, 2018

@solongordon solongordon requested review from cockroachdb/distsql-prs as code owners Oct 8, 2018

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cockroach-teamcity commented Oct 8, 2018

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@solongordon solongordon merged commit ad11a25 into cockroachdb:release-2.1 Oct 8, 2018
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@solongordon solongordon deleted the solongordon:backport2.1-30216 branch Oct 9, 2018

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