I really appreciate for the modification. I also believe XLOG_NOOP is cool to maintains XLOG format consistent. I'll continue to write a code to produce incremental log record from the full page writes as well as too maintain CRC, XLOOG_NOOP and other XLOG locations, I also found that you've added information on btree strip log records, which anables to produce corresponding incremental logs from the full page writes.
2007/5/21, Tom Lane <[EMAIL PROTECTED]>:
Koichi Suzuki <[EMAIL PROTECTED]> writes: > As replied to "Patch queue triage" by Tom, here's simplified patch to > mark WAL record as "compressable", with no increase in WAL itself. > Compression/decompression commands will be posted separately to PG > Foundary for further review. Applied with some minor modifications. I didn't like the idea of suppressing the sanity-check on WAL record length; I think that's fairly important. Instead, I added a provision for an XLOG_NOOP WAL record type that can be used to fill in the extra space. The way I envision that working is that the compressor removes backup blocks and converts each compressible WAL record to have the same contents and length it would've had if written without backup blocks. Then, it inserts an XLOG_NOOP record with length set to indicate the amount of extra space that needs to be chewed up -- but in the compressed version of the WAL file, XLOG_NOOP's "data area" is not actually stored. The decompressor need only scan the file looking for XLOG_NOOP and insert the requisite number of zero bytes (and maybe recompute the XLOG_NOOP's CRC, depending on whether you want it to be valid for the short-format record in the compressed file). There will also be some games to be played for WAL page boundaries, but you had to do that anyway. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
-- ------ Koichi Suzuki ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings