RE: [Patch] Optimize dropping of relation buffers using dlist - Mailing list pgsql-hackers

From: Jamison, Kirk/ジャミソン カーク <k.jamison@fujitsu.com>
> I added comment in 0004 the limitation of optimization when there are TOAST
> relations that use NON-PLAIN strategy. i.e. The optimization works if the data
> types used are integers, OID, bytea, etc. But for TOAST-able data types like text,
> the optimization will be skipped and force a full scan during recovery.

bytea is a TOAST-able type.


+    /*
+     * Enter the optimization if the total number of blocks to be
+     * invalidated for all relations is below the full scan threshold.
+     */
+    if (cached && nBlocksToInvalidate < BUF_DROP_FULL_SCAN_THRESHOLD)

Checking cached here doesn't seem to be necessary, because if cached is false, the control goes to the full scan path
asbelow:
 

+            if (!cached)
+                goto buffer_full_scan;
+


Regards
Takayuki Tsunakawa