Running 'CREATE EXTENSION postgis' on my machine after enabling
auto_explain results in the process writing gigabytes of logs
keeping the CPU busy for tens of minutes.
RhodiumToad on IRC explained to me:
< RhodiumToad> the extension script code doesn't split the script
into statements itself, it passes the whole thing to the
raw parser and gets back a list of statements
As a result, each INSERT statement found in the PostGIS extension script
results in the whole extension script (including copyright notices!)
being dumped in the logs ("Query Text:").
It is also impossible to know which actual statement the plan refers
to as always the same full script is dumped.
PostGIS has ~4k INSERT statements in its extension script.
While the CREATE EXTENSION statement would take under one second to
complete with auto_explain disabled, here's the state of my machine
at this very moment, with auto_explain enabled:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
8905 strk 20 0 4637680 186348 62448 R 99.5 1.1 14:41.26 postgres: strk dbtopo [local] CREATE EXTENSION
-rw------- 1 strk strk 10228477364 Nov 18 12:37 /tmp/pg93.log
It's been running for almost 15 minutes now, and filling up the logfile.
Could this be considered a bug in auto_explain ?
--strk;
() Free GIS & Flash consultant/developer
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