Re: BUG #12292: index row size 1480 exceeds maximum 1352 for index

robert(dot)thaler(at)cellent(dot)at writes:
> I tried to upgrade from postgres 9.3.5 and imported a database export
> created by pg_dump. the import shows the following error:
> ERROR: index row size 1480 exceeds
> maximum 1352 for index "idx_sm_post_content"

I've looked into this (thanks to Robert for the test data), and the short
answer is that commit 36a35c55 approximately halved GinMaxItemSize:

#define GinMaxItemSize \
- MAXALIGN_DOWN(((BLCKSZ - SizeOfPageHeaderData - \
- MAXALIGN(sizeof(GinPageOpaqueData))) / 3 - sizeof(ItemIdData)))
+ Min(INDEX_SIZE_MASK, \
+ MAXALIGN_DOWN(((BLCKSZ - SizeOfPageHeaderData - \
+ MAXALIGN(sizeof(GinPageOpaqueData))) / 6 - sizeof(ItemIdData))))

What was the rationale for deciding that GIN has to be able to fit six
tuples per page??? This is going to create serious dump/reload hazards
for a lot of users.

regards, tom lane