Re: Re: Loading optimization - Mailing list pgsql-general

From Tom Lane
Subject Re: Re: Loading optimization
Date
Msg-id 13250.979258201@sss.pgh.pa.us
Whole thread Raw
In response to RE: Re: Loading optimization  ("Mikheev, Vadim" <vmikheev@SECTORBASE.COM>)
List pgsql-general
"Mikheev, Vadim" <vmikheev@SECTORBASE.COM> writes:
> Also, WAL doesn't prevent zero blocks in files after crash - I didn't
> want to fsync log on each new block allocation, - but this shouldn't
> be a problem (except of lost disk space), afair scans are smart to
> handle it, Tom?

This is OK for table files, unless someone's broken the code that will
auto-initialize a zero page when it comes across one.

I had a note to myself saying that zeroed pages in indexes may not be
OK, but I'm not sure if that's really a risk or not.  btree, at least,
never does any linear scans of an index file; it can only visit pages
that are linked to by parent or sibling links.  If we are careful that
we init a btree page before we modify its sibling(s) and parent, we
should be OK.

            regards, tom lane

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