Hi, I'm working on microvacuum for gist access method. Briefly microvacuum includes two steps: 1. When search tells us that the tuple is invisible to all transactions it is marked LP_DEAD and page is marked as "has dead tuples", 2. Then, when insert touches full page which has dead tuples it calls microvacuum instead of splitting page. You can find a kind of review here [1].
While writing patch, I found strange GISTPageOpaqueData flag - F_TUPLES_DELETED <http://doxygen.postgresql.org/gist_8h.html#a23812efd70313b9b10ae61376e2594f6> . Its description looks like it is the same for BTP_HAS_GARBAGE <http://doxygen.postgresql.org/nbtree_8h.html#a3b7c77849276ff8617edc1f84441c230> #define F_TUPLES_DELETED (1 << 2) /* some tuples on the page are dead */ #define BTP_HAS_GARBAGE (1 << 6) /* page has LP_DEAD tuples */ But it's definitely not the same things. I found only two mentions of this flag. Function GistMarkTuplesDeleted <http://doxygen.postgresql.org/gist_8h.html#a96fc3c6bb5aecfc8d2818b7010d68aac> sets the flag after dead tuples deletion. Do anyone need it at all? I found no place where this flag is checked. Is it correct using of the flag? I need an advice, what would be better: - to add new flag like F_HAS_GARBAGE, - or to delete all mentions of F_TUPLES_DELETED and use it in gist microvacuum. [1] http://www.google-melange.com/gsoc/proposal/public/google/gsoc2015/ivanitskiy_ilya/5629499534213120 -- Best regards, Lubennikova Anastasia
