/*
* Given a BRIN index page, initialize it if necessary, and record it into the
* FSM if necessary. Return value is true if the FSM itself needs "vacuuming".
* The main use for this is when, during vacuuming, an uninitialized page is
* found, which could be the result of relation extension followed by a crash
* before the page can be used.
*/
bool
brin_page_cleanup(Relation idxrel, Buffer buf)
{
Page page = BufferGetPage(buf);
Size freespace;
/*
* If a page was left uninitialized, initialize it now; also record it in
* FSM.
*
* Somebody else might be extending the relation concurrently. To avoid
* re-initializing the page before they can grab the buffer lock, we
* acquire the extension lock momentarily. Since they hold the extension
* lock from before getting the page and after its been initialized, we're
* sure to see their initialization.
*/
if (PageIsNew(page))
{
LockRelationForExtension(idxrel, ShareLock);
UnlockRelationForExtension(idxrel, ShareLock);
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
if (PageIsNew(page))
{
brin_initialize_empty_new_buffer(idxrel, buf);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
return true;
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
}
/* Nothing to be done for non-regular index pages */
if (BRIN_IS_META_PAGE(BufferGetPage(buf)) ||
BRIN_IS_REVMAP_PAGE(BufferGetPage(buf)))
return false;
/* Measure free space and record it */
freespace = br_page_get_freespace(page);
if (freespace > GetRecordedFreeSpace(idxrel, BufferGetBlockNumber(buf)))
{
RecordPageWithFreeSpace(idxrel, BufferGetBlockNumber(buf), freespace);
return true;
}
return false;
}
/*
* Mask a BRIN page before doing consistency checks.
*/
void
brin_mask(char *pagedata, BlockNumber blkno)
{
Page page = (Page) pagedata;
PageHeader pagehdr = (PageHeader) page;
mask_page_lsn_and_checksum(page);
mask_page_hint_bits(page);
/*
* Regular brin pages contain unused space which needs to be masked.
* Similarly for meta pages, but mask it only if pd_lower appears to have
* been set correctly.
*/
if (BRIN_IS_REGULAR_PAGE(page) ||
(BRIN_IS_META_PAGE(page) && pagehdr->pd_lower > SizeOfPageHeaderData))
{
mask_unused_space(page);
}
}
