Re: Permute underscore separated components of columns before fuzzy matching

Hello Arne,

The goal of supporting words-switching hints sounds interesting and I've tried to apply your patch.
The patch was applied smoothly to the latest master and check-world reported no problems. Although I had problems after trying to test the new functionality.

I tried to simply mix words in pg_stat_activity.wait_event_type:

postgres=# select wait_type_event from pg_stat_activity ;
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
2023-07-06 14:12:35.968 MSK [1480] ERROR:  column "wait_type_event" does not exist at character 8
2023-07-06 14:12:35.968 MSK [1480] HINT:  Perhaps you meant to reference the column "pg_stat_activity.wait_event_type".
2023-07-06 14:12:35.968 MSK [1480] STATEMENT:  select wait_type_event from pg_stat_activity ;
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
WARNING:  detected write past chunk end in MessageContext 0x559d668aaf30
ERROR:  column "wait_type_event" does not exist
LINE 1: select wait_type_event from pg_stat_activity ;
               ^
HINT:  Perhaps you meant to reference the column "pg_stat_activity.wait_event_type".
postgres=#

So the desired hint is really there, but thgether with looots of warnings. For sure these should not be be encountered.

And no, this is not some kind of side problem brought by some other commit. The same request on a plain master branch performs without these warnings:

postgres=# select wait_type_event from pg_stat_activity ;
2023-07-06 14:10:17.171 MSK [22431] ERROR:  column "wait_type_event" does not exist at character 8
2023-07-06 14:10:17.171 MSK [22431] STATEMENT:  select wait_type_event from pg_stat_activity ;
ERROR:  column "wait_type_event" does not exist
LINE 1: select wait_type_event from pg_stat_activity ;