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a17da19ed9
SPI_execute() and related functions create a CachedPlan, execute it once, and immediately discard it, so that the functionality offered by plancache.c is of no value in this code path. And performance measurements show that the extra data copying and invalidation checking done by plancache.c slows down simple queries by 10% or more compared to 9.1. However, enough of the SPI code is shared with functions that do need plan caching that it seems impractical to bypass plancache.c altogether. Instead, let's invent a variant version of cached plans that preserves 99% of the API but doesn't offer any of the actual functionality, nor the overhead. This puts SPI_execute() performance back on par, or maybe even slightly better, than it was before. This change should resolve recent complaints of performance degradation from Dong Ye, Pavel Stehule, and others. By avoiding data copying, this change also reduces the amount of memory needed to execute many-statement SPI_execute() strings, as for instance in a recent complaint from Tomas Vondra. An additional benefit of this change is that multi-statement SPI_execute() query strings are now processed fully serially, that is we complete execution of earlier statements before running parse analysis and planning on following ones. This eliminates a long-standing POLA violation, in that DDL that affects the behavior of a later statement will now behave as expected. Back-patch to 9.2, since this was a performance regression compared to 9.1. (In 9.2, place the added struct fields so as to avoid changing the offsets of existing fields.) Heikki Linnakangas and Tom Lane |
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| bootstrap | ||
| catalog | ||
| commands | ||
| datatype | ||
| executor | ||
| foreign | ||
| lib | ||
| libpq | ||
| mb | ||
| nodes | ||
| optimizer | ||
| parser | ||
| port | ||
| portability | ||
| postmaster | ||
| regex | ||
| replication | ||
| rewrite | ||
| snowball | ||
| storage | ||
| tcop | ||
| tsearch | ||
| utils | ||
| .gitignore | ||
| c.h | ||
| fmgr.h | ||
| funcapi.h | ||
| getaddrinfo.h | ||
| getopt_long.h | ||
| Makefile | ||
| miscadmin.h | ||
| pg_config.h.in | ||
| pg_config.h.win32 | ||
| pg_config_manual.h | ||
| pg_trace.h | ||
| pgstat.h | ||
| pgtime.h | ||
| port.h | ||
| postgres.h | ||
| postgres_ext.h | ||
| postgres_fe.h | ||
| rusagestub.h | ||
| windowapi.h | ||