Possible micro-optimization in CacheInvalidateHeapTuple

[Jim Nasby]

CacheInvalidateHeapTuple currently does the following tests first; would there be a performance improvement to testing the system relation case first? We're almost never in bootstrap mode, so that test is almost always a waste. Is there any reason not to switch the two?

/* Do nothing during bootstrap */
if (IsBootstrapProcessingMode())
return;

/*
* We only need to worry about invalidation for tuples that are in system
* relations; user-relation tuples are never in catcaches and can't affect
* the relcache either.
*/
if (!IsSystemRelation(relation))
return;

[Tom Lane]

Post by Jim Nasby
CacheInvalidateHeapTuple currently does the following tests first; would there be a performance improvement to testing the system relation case first? We're almost never in bootstrap mode, so that test is almost always a waste. Is there any reason not to switch the two?
/* Do nothing during bootstrap */
if (IsBootstrapProcessingMode())
return;
/*
* We only need to worry about invalidation for tuples that are in system
* relations; user-relation tuples are never in catcaches and can't affect
* the relcache either.
*/
if (!IsSystemRelation(relation))
return;

You're assuming that IsSystemRelation() is safe to apply during bootstrap
mode. Even if it is, I don't see the point of messing with this.
IsBootstrapProcessingMode() is a macro expanding to one comparison
instruction.

regards, tom lane

[Jim Nasby]

Post by Tom Lane

Post by Jim Nasby
CacheInvalidateHeapTuple currently does the following tests first; would there be a performance improvement to testing the system relation case first? We're almost never in bootstrap mode, so that test is almost always a waste. Is there any reason not to switch the two?
/* Do nothing during bootstrap */
if (IsBootstrapProcessingMode())
return;
/*
* We only need to worry about invalidation for tuples that are in system
* relations; user-relation tuples are never in catcaches and can't affect
* the relcache either.
*/
if (!IsSystemRelation(relation))
return;

You're assuming that IsSystemRelation() is safe to apply during bootstrap
mode. Even if it is, I don't see the point of messing with this.
IsBootstrapProcessingMode() is a macro expanding to one comparison
instruction.

Comment patch to that effect attached.