I read it many times but I'am not entirely familiar with concepts of range table and I'am not sure to fully understant all implications. For now I have a workaround by parsing only plan's target list and by checking if resorigtbl is equal to oid of my table. The main drawback is that I can't detect column if it is used in a function or an aggregator. Thanks anyway for your help.
Le mar. 3 juil. 2018 à 12:38, Laurenz Albe <laurenz.a...@cybertec.at> a écrit : > Mathieu PUJOL wrote: > > I understand that I should also use varno to check which table is > referenced by varattno. In case of Join, aggregation, etc. Sometimes I get > a number or INNER_VAR or OUTER_VAR. > > I am lost on how i could resolve this. > > I understand that OUTER_VAR/INNER_VAR are related to joins sub plans. Is > outer related to left plan and inner to right plan ? In this case varattno > is index of target list of subplan ? > > When varno is an index how to retrieve table info ? > > I have no deep understanding of these things. > > Maybe the following comment from include/nodes/primnodes.h can help: > > /* > * Var - expression node representing a variable (ie, a table column) > * > * Note: during parsing/planning, varnoold/varoattno are always just copies > * of varno/varattno. At the tail end of planning, Var nodes appearing in > * upper-level plan nodes are reassigned to point to the outputs of their > * subplans; for example, in a join node varno becomes INNER_VAR or > OUTER_VAR > * and varattno becomes the index of the proper element of that subplan's > * target list. Similarly, INDEX_VAR is used to identify Vars that > reference > * an index column rather than a heap column. (In ForeignScan and > CustomScan > * plan nodes, INDEX_VAR is abused to signify references to columns of a > * custom scan tuple type.) In all these cases, varnoold/varoattno hold > the > * original values. The code doesn't really need varnoold/varoattno, but > they > * are very useful for debugging and interpreting completed plans, so we > keep > * them around. > */ > #define INNER_VAR 65000 /* reference to inner subplan */ > #define OUTER_VAR 65001 /* reference to outer subplan */ > #define INDEX_VAR 65002 /* reference to index column */ > > #define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR) > > Yours, > Laurenz Albe > -- > Cybertec | https://www.cybertec-postgresql.com >
