Find attached updated patch:
. Use structure to include relation name.
. Split into a separate patch rename of "StringInfoData buf".
2019-11-27 20:04:53.640 CST [14244] ERROR: canceling statement due to statement timeout
2019-11-27 20:04:53.640 CST [14244] CONTEXT: block 2314 of relation t
2019-11-27 20:04:53.640 CST [14244] STATEMENT: vacuum t;
I tried to use BufferGetTag() to avoid using a 2ndary structure, but fails if
the buffer is not pinned.