Re: Cached plans and statement generalization

On Thu, May 11, 2017 at 10:41:45PM +0300, Konstantin Knizhnik wrote:
> This is why I have provided second implementation which replace
> literals with parameters after raw parsing. Certainly it is slower
> than first approach. But still provide significant advantage in
> performance: more than two times at pgbench. Then I tried to run
> regression tests and find several situations where type analysis is
> not correctly performed in case of replacing literals with parameters.

So the issue is that per-command output from the parser, SelectStmt,
only has strings for identifers, e.g. table and column names, so you
can't be sure it is the same as the cached entry you matched. I suppose
if you cleared the cache every time someone created an object or changed
search_path, it might work.

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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