Horton

Re: JIT & function naming

Konstantin Knizhnik <k.knizhnik@postgrespro.ru>

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From: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
To: pgsql-hackers@postgresql.org
Date: 2017-09-03T07:04:32Z
Lists: pgsql-hackers 
On 09/03/2017 02:59 AM, Andres Freund wrote:
> Hi,
>
> On 2017-08-31 23:41:31 -0700, Andres Freund wrote:
>> I previously had an early prototype of JITing [1] expression evaluation
>> and tuple deforming.  I've since then worked a lot on this.
>>
>> Here's an initial, not really pretty but functional, submission.
> One of the things I'm not really happy about yet is the naming of the
> generated functions. Those primarily matter when doing profiling, where
> the function name will show up when the profiler supports JIT stuff
> (e.g. with a patch I proposed to LLVM that emits perf compatible output,
> there's also existing LLVM support for a profiler by intel and
> oprofile).
>
> Currently there's essentially a per EState counter and the generated
> functions get named deform$n and evalexpr$n. That allows for profiling
> of a single query, because different compiled expressions are
> disambiguated. It even allows to run the same query over and over, still
> giving meaningful results.  But it breaks down when running multiple
> queries while profiling - evalexpr0 can mean something entirely
> different for different queries.
>
> The best idea I have so far would be to name queries like
> evalexpr_$fingerprint_$n, but for that we'd need fingerprinting support
> outside of pg_stat_statement, which seems painful-ish.
>
> Perhaps somebody has a better idea?

As far as I understand we do not need precise fingerprint.
So may be just calculate some lightweight fingerprint?
For example take query text (es_sourceText from EText), replace all non-alphanumeric characters spaces with '_' and take first N (16?) characters of the result?
It seems to me that in most cases it will help to identify the query...


-- 
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Improve JIT docs.

  2. Add documentation for the JIT feature.

  3. Add EXPLAIN support for JIT.

  4. Add inlining support to LLVM JIT provider.

  5. JIT tuple deforming in LLVM JIT provider.

  6. Add FIELDNO_* macro designating offset into structs required for JIT.

  7. Add expression compilation support to LLVM JIT provider.

  8. Expand list of synchronized types and functions in LLVM JIT provider.

  9. Add helpers for emitting LLVM IR.

  10. Basic planner and executor integration for JIT.

  11. Debugging and profiling support for LLVM JIT provider.

  12. Support for optimizing and emitting code in LLVM JIT provider.

  13. Add file containing extensions of the LLVM C API.

  14. Basic JIT provider and error handling infrastructure.

  15. Add configure infrastructure (--with-llvm) to enable LLVM support.

  16. Add C++ support to configure.

  17. Add PGAC_PROG_VARCC_VARFLAGS_OPT autoconf macro.

  18. Fix VM buffer pin management in heap_lock_updated_tuple_rec().

  19. Allow tupleslots to have a fixed tupledesc, use in executor nodes.

  20. Expression evaluation based aggregate transition invocation.

  21. Perform slot validity checks in a separate pass over expression.

  22. Rely on executor utils to build targetlist for DML RETURNING.

  23. Refer to OS X as "macOS", except for the port name which is still "darwin".