Some more information...
First of all I found out that marking PL/pgSQL function as immutable significantly increase speed of its execution:
19808 ms vs. 27594. It happens because exec_eval_simple_expr is taken snapshot if function is volatile (default).
I wonder if PL/pgSQL compiler can detect that evaluated expression itself is actually immutable and there is no need to take snapshot
for each invocation of this function. Also I have tried yet another PL language - JavaScript, which is now new outsider, despite to the fact that
v8 JIT compiler is very good.
Implementation
| time (ms)
|
PL/v8
| 41550
|
| PL/Lua | 32220 |
| PL/pgSQL | 19808 |
| C/SPI | 9406 |
| SQL | 7399 |
SQL (JIT)
| 5532
|
| С/coreAPI | 2873 |
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Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company