Greetings, * Andreas Joseph Krogh (andreas@xxxxxxxxxx) wrote: > Aha, so enabling CRC causes hint-bits to be written causing extra WAL-logging, > which woudn't be the case without CRC enabled? > Thanks for pointing that out. Yes, having checksums enabled forces logging of hint bits. You can enable wal_log_hints independently too, without having checksums, to see what kind of an impact it'll have on your environment. A useful documentation update might be: --- With checksums enabled, wal_log_hints <link to the GUC's documentation> will be enabled and each page read or write will involve calculating the checksum for the page. --- I'd probably just replace the "Enabling checksums may incur a noticeable performance penalty" with the above, as it should be clear that doing more work implies an impact on performance and that avoids the whole question of trying to characterize in a general way something that can't be generalized (as it's workload dependent). Thanks! Stephen
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