On Sun, Jan 14, 2018 at 6:57 AM, Amit Khandekar <amitdkhan...@gmail.com> wrote: > Even where partitions are present, in the usual case where there are > no transition tables we won't require per-leaf map at all [1]. So I > think we should keep mt_per_sub_plan_maps only for the case where > per-leaf map is not allocated. And we will not allocate > mt_per_sub_plan_maps when mt_per_leaf_maps is needed. In other words, > exactly one of the two maps will be allocated. > > This is turning out to be close to what's already there in the last > patch versions: use a single map array, and an offsets array. The > difference is : in the patch I am using the *same* variable for the > two maps. Where as, now we are talking about two different array > variables for maps, but only allocating one of them. > > Are you ok with this ? I think the thing you were against was to have > a common *variable* for two purposes. But above, I am saying we have > two variables but assign a map array to only *one* of them and leave > the other unused.
Yes, I'm OK with that. > Regarding the on-demand map allocation .... > Where mt_per_sub_plan_maps is allocated, we won't have the on-demand > allocation: all the maps will be allocated initially. The reason is > becaues the map_is_required array is only per-leaf. Or else, again, we > need to keep another map_is_required array for per-subplan. May be we > can support the on-demand stuff for subplan maps also, but only as a > separate change after we are done with update-partition-key. Sure. > Regarding mt_per_leaf_tupconv_required, I am thinking we can make it a > bool array, and name it : mt_per_leaf_map_not_required. When it is > true for a given index, it means, we have already called > convert_tuples_by_name() and it returned NULL; i.e. it means we are > sure that map is not required. A false value means we need to call > convert_tuples_by_name() if it is NULL, and then set > mt_per_leaf_map_not_required to (map == NULL). OK. > Instead of a bool array, we can even make it a Bitmapset. But I think > access would become slower as compared to array, particularly because > it is going to be a heavily used function. It probably makes little difference -- the Bitmapset will be more compact (which saves time) but involve function calls (which cost time). -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
