Function _bitmap_write_new_bitmapwords

src/backend/access/bitmap/bitmapinsert.c:1228–1458

* _bitmap_write_new_bitmapwords() -- write a given buffer of new bitmap words * into the end of bitmap page(s). * * If the last bitmap page does not have enough space for all these new * words, new pages will be allocated here. * * We consider a write to one bitmap page as one atomic-action WAL * record. The WAL record for the write to the last bitmap page also * includes updates on the l

 * during WAL logic replay.
 */
static void
_bitmap_write_new_bitmapwords(Relation rel,
							  Buffer lovBuffer, OffsetNumber lovOffset,
							  BMTIDBuffer* buf, bool use_wal)
{
	Page		lovPage;
	BMLOVItem	lovItem;
	bool		first_page_needs_init = false;
	List	   *perpage_buffers = NIL;
	List	   *perpage_xlrecs = NIL;
	ListCell   *lcb;

	lovPage = BufferGetPage(lovBuffer);
	lovItem = (BMLOVItem) PageGetItem(lovPage,
									  PageGetItemId(lovPage, lovOffset));

	/*
	 * Write changes to bitmap pages, if needed. (We might get away by
	 * updating just the last words stored on the LOV item.)
	 */
	if (buf->curword > 0)
	{
		ListCell   *lcp;
		BlockNumber first_blkno;
		BlockNumber last_blkno;
		List	   *perpage_tmppages = NIL;
		bool		is_first;
		ListCell   *buffer_cell;
		int			start_wordno;

		/*
		 * Write bitmap words, one page at a time, allocating new pages as
		 * required.
		 */
		is_first = true;
		start_wordno = 0;
		do
		{
			Buffer		bitmapBuffer;
			bool		bitmapBufferNeedsInit = false;
			Page		bitmapPage;
			BMBitmapOpaque	bitmapPageOpaque;
			uint32		numFreeWords;
			uint32		words_written;
			xl_bm_bitmapwords_perpage *xlrec_perpage;
			Page		tmppage = NULL;

			if (is_first && lovItem->bm_lov_head != InvalidBlockNumber)
			{
				bitmapBuffer = _bitmap_getbuf(rel, lovItem->bm_lov_tail, BM_WRITE);

				/* Append to an existing LOV page as much as fits */
				bitmapPage = BufferGetPage(bitmapBuffer);
				bitmapPageOpaque =
					(BMBitmapOpaque) PageGetSpecialPointer(bitmapPage);

				numFreeWords = BM_NUM_OF_HRL_WORDS_PER_PAGE -
					bitmapPageOpaque->bm_hrl_words_used;