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

robert.thaler@cellent.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