Zach Amsden 0715a303ea IMPALA-4729: Implement REPLACE() ...

This turned out to be slightly non-trivial as REPLACE is already a
keyword, and thus the parser needs to be tweaked to allow this,
since function names act as bare identifiers.

It was difficult to get this to match performance of regexp_replace.
For expanding patterns, the fact that regexp_replace copies the
expansion inline means that it may in fact win on large strings
with sparse matches that are > dcache size apart.  Let's leave
optimizing that for later.

Testing: Added a full test for maximum size strings and got most
of the boundary conditions I could identify.  Manually ran queries
on TPC-H dataset in impala to verify both performance and correctness.
Added large string and exprs.test test clauses and ran the tests to
verify they work as expected.

Change-Id: I1780a7d8fee6d0db9dad148217fb6eb10f773329
Reviewed-on: http://gerrit.cloudera.org:8080/5776
Reviewed-by: Dan Hecht <dhecht@cloudera.com>
Tested-by: Impala Public Jenkins

2017-02-15 01:33:23 +00:00

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