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Update clog.h

This commit is contained in:
bjyb 2023-09-17 05:06:52 +08:00
parent ccb26b2152
commit 73189d9112
1 changed files with 6 additions and 0 deletions
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6
src/include/access/clog.h
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@ -27,6 +27,12 @@
* and page numbers in TruncateCLOG (see CLOGPagePrecedes).
*/
/*
Because of compression, the storage on the disk is greatly reduced, and the compression ratio can reach 2-4 times.
Some blocks in the data are stored, and the max and min values of the block data are recorded, and block skipping query can be performed during query.
When querying, instead of loading all disk data into memory, columns are selected to load the required data according to the offset in the recorded skiplist, reducing IO.
*/
/* We need two bits per xact, so four xacts fit in a byte */
#define CLOG_BITS_PER_XACT 2
#define CLOG_XACTS_PER_BYTE 4