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Columnar: reserve metapage flag for UNLOGGED support. (#5237) 

Reserve space in the metapage for a flag to support UNLOGGED tables in
the future without a metapage upgrade.
pull/5239/head^2
jeff-davis 2021-09-03 08:40:55 -07:00 committed by GitHub
parent f67574496c
commit cc58b58f73
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1 changed files with 14 additions and 0 deletions
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14
src/backend/columnar/columnar_storage.c
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@ -70,6 +70,19 @@ typedef struct ColumnarMetapage
uint64 reservedStripeId; /* first unused stripe id */
uint64 reservedRowNumber; /* first unused row number */
uint64 reservedOffset; /* first unused byte offset */
/*
* Flag set to true in the init fork. After an unlogged table reset (due
* to a crash), the init fork will be copied over the main fork. When
* trying to read an unlogged table, if this flag is set to true, we must
* clear the metadata for the table (because the actual data is gone,
* too), and clear the flag. We can cross-check that the table is
* UNLOGGED, and that the main fork is at the minimum size (no actual
* data).
*
* XXX: Not used yet; reserved field for later support for UNLOGGED.
*/
bool unloggedReset;
} ColumnarMetapage;
@ -163,6 +176,7 @@ ColumnarStorageInit(SMgrRelation srel, uint64 storageId)
metapage.reservedStripeId = COLUMNAR_FIRST_STRIPE_ID;
metapage.reservedRowNumber = COLUMNAR_FIRST_ROW_NUMBER;
metapage.reservedOffset = ColumnarFirstLogicalOffset;
metapage.unloggedReset = false;
memcpy_s(page + phdr->pd_lower, phdr->pd_upper - phdr->pd_lower,
(char *) &metapage, sizeof(ColumnarMetapage));
phdr->pd_lower += sizeof(ColumnarMetapage);