Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * partitionfuncs.c
       4             :  *    Functions for accessing partition-related metadata
       5             :  *
       6             :  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/utils/adt/partitionfuncs.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : 
      16             : #include "postgres.h"
      17             : 
      18             : #include "access/htup_details.h"
      19             : #include "catalog/partition.h"
      20             : #include "catalog/pg_class.h"
      21             : #include "catalog/pg_inherits.h"
      22             : #include "catalog/pg_type.h"
      23             : #include "funcapi.h"
      24             : #include "utils/fmgrprotos.h"
      25             : #include "utils/lsyscache.h"
      26             : #include "utils/syscache.h"
      27             : 
      28             : /*
      29             :  * Checks if a given relation can be part of a partition tree.  Returns
      30             :  * false if the relation cannot be processed, in which case it is up to
      31             :  * the caller to decide what to do, by either raising an error or doing
      32             :  * something else.
      33             :  */
      34             : static bool
      35        2388 : check_rel_can_be_partition(Oid relid)
      36             : {
      37             :     char        relkind;
      38             :     bool        relispartition;
      39             : 
      40             :     /* Check if relation exists */
      41        2388 :     if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relid)))
      42          18 :         return false;
      43             : 
      44        2370 :     relkind = get_rel_relkind(relid);
      45        2370 :     relispartition = get_rel_relispartition(relid);
      46             : 
      47             :     /* Only allow relation types that can appear in partition trees. */
      48        2370 :     if (!relispartition && !RELKIND_HAS_PARTITIONS(relkind))
      49         574 :         return false;
      50             : 
      51        1796 :     return true;
      52             : }
      53             : 
      54             : /*
      55             :  * pg_partition_tree
      56             :  *
      57             :  * Produce a view with one row per member of a partition tree, beginning
      58             :  * from the top-most parent given by the caller.  This gives information
      59             :  * about each partition, its immediate partitioned parent, if it is
      60             :  * a leaf partition and its level in the hierarchy.
      61             :  */
      62             : Datum
      63         946 : pg_partition_tree(PG_FUNCTION_ARGS)
      64             : {
      65             : #define PG_PARTITION_TREE_COLS  4
      66         946 :     Oid         rootrelid = PG_GETARG_OID(0);
      67             :     FuncCallContext *funcctx;
      68             :     List       *partitions;
      69             : 
      70             :     /* stuff done only on the first call of the function */
      71         946 :     if (SRF_IS_FIRSTCALL())
      72             :     {
      73             :         MemoryContext oldcxt;
      74             :         TupleDesc   tupdesc;
      75             : 
      76             :         /* create a function context for cross-call persistence */
      77         202 :         funcctx = SRF_FIRSTCALL_INIT();
      78             : 
      79         202 :         if (!check_rel_can_be_partition(rootrelid))
      80          36 :             SRF_RETURN_DONE(funcctx);
      81             : 
      82             :         /* switch to memory context appropriate for multiple function calls */
      83         166 :         oldcxt = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
      84             : 
      85             :         /*
      86             :          * Find all members of inheritance set.  We only need AccessShareLock
      87             :          * on the children for the partition information lookup.
      88             :          */
      89         166 :         partitions = find_all_inheritors(rootrelid, AccessShareLock, NULL);
      90             : 
      91         166 :         if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
      92           0 :             elog(ERROR, "return type must be a row type");
      93         166 :         funcctx->tuple_desc = tupdesc;
      94             : 
      95             :         /* The only state we need is the partition list */
      96         166 :         funcctx->user_fctx = (void *) partitions;
      97             : 
      98         166 :         MemoryContextSwitchTo(oldcxt);
      99             :     }
     100             : 
     101             :     /* stuff done on every call of the function */
     102         910 :     funcctx = SRF_PERCALL_SETUP();
     103         910 :     partitions = (List *) funcctx->user_fctx;
     104             : 
     105         910 :     if (funcctx->call_cntr < list_length(partitions))
     106             :     {
     107             :         Datum       result;
     108         744 :         Datum       values[PG_PARTITION_TREE_COLS] = {0};
     109         744 :         bool        nulls[PG_PARTITION_TREE_COLS] = {0};
     110             :         HeapTuple   tuple;
     111         744 :         Oid         parentid = InvalidOid;
     112         744 :         Oid         relid = list_nth_oid(partitions, funcctx->call_cntr);
     113         744 :         char        relkind = get_rel_relkind(relid);
     114         744 :         int         level = 0;
     115         744 :         List       *ancestors = get_partition_ancestors(relid);
     116             :         ListCell   *lc;
     117             : 
     118             :         /*
     119             :          * Form tuple with appropriate data.
     120             :          */
     121             : 
     122             :         /* relid */
     123         744 :         values[0] = ObjectIdGetDatum(relid);
     124             : 
     125             :         /* parentid */
     126         744 :         if (ancestors != NIL)
     127         614 :             parentid = linitial_oid(ancestors);
     128         744 :         if (OidIsValid(parentid))
     129         614 :             values[1] = ObjectIdGetDatum(parentid);
     130             :         else
     131         130 :             nulls[1] = true;
     132             : 
     133             :         /* isleaf */
     134         744 :         values[2] = BoolGetDatum(!RELKIND_HAS_PARTITIONS(relkind));
     135             : 
     136             :         /* level */
     137         744 :         if (relid != rootrelid)
     138             :         {
     139         824 :             foreach(lc, ancestors)
     140             :             {
     141         824 :                 level++;
     142         824 :                 if (lfirst_oid(lc) == rootrelid)
     143         578 :                     break;
     144             :             }
     145             :         }
     146         744 :         values[3] = Int32GetDatum(level);
     147             : 
     148         744 :         tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
     149         744 :         result = HeapTupleGetDatum(tuple);
     150         744 :         SRF_RETURN_NEXT(funcctx, result);
     151             :     }
     152             : 
     153             :     /* done when there are no more elements left */
     154         166 :     SRF_RETURN_DONE(funcctx);
     155             : }
     156             : 
     157             : /*
     158             :  * pg_partition_root
     159             :  *
     160             :  * Returns the top-most parent of the partition tree to which a given
     161             :  * relation belongs, or NULL if it's not (or cannot be) part of any
     162             :  * partition tree.
     163             :  */
     164             : Datum
     165          96 : pg_partition_root(PG_FUNCTION_ARGS)
     166             : {
     167          96 :     Oid         relid = PG_GETARG_OID(0);
     168             :     Oid         rootrelid;
     169             :     List       *ancestors;
     170             : 
     171          96 :     if (!check_rel_can_be_partition(relid))
     172          36 :         PG_RETURN_NULL();
     173             : 
     174             :     /* fetch the list of ancestors */
     175          60 :     ancestors = get_partition_ancestors(relid);
     176             : 
     177             :     /*
     178             :      * If the input relation is already the top-most parent, just return
     179             :      * itself.
     180             :      */
     181          60 :     if (ancestors == NIL)
     182          12 :         PG_RETURN_OID(relid);
     183             : 
     184          48 :     rootrelid = llast_oid(ancestors);
     185          48 :     list_free(ancestors);
     186             : 
     187             :     /*
     188             :      * "rootrelid" must contain a valid OID, given that the input relation is
     189             :      * a valid partition tree member as checked above.
     190             :      */
     191             :     Assert(OidIsValid(rootrelid));
     192          48 :     PG_RETURN_OID(rootrelid);
     193             : }
     194             : 
     195             : /*
     196             :  * pg_partition_ancestors
     197             :  *
     198             :  * Produces a view with one row per ancestor of the given partition,
     199             :  * including the input relation itself.
     200             :  */
     201             : Datum
     202        4586 : pg_partition_ancestors(PG_FUNCTION_ARGS)
     203             : {
     204        4586 :     Oid         relid = PG_GETARG_OID(0);
     205             :     FuncCallContext *funcctx;
     206             :     List       *ancestors;
     207             : 
     208        4586 :     if (SRF_IS_FIRSTCALL())
     209             :     {
     210             :         MemoryContext oldcxt;
     211             : 
     212        2090 :         funcctx = SRF_FIRSTCALL_INIT();
     213             : 
     214        2090 :         if (!check_rel_can_be_partition(relid))
     215         520 :             SRF_RETURN_DONE(funcctx);
     216             : 
     217        1570 :         oldcxt = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
     218             : 
     219        1570 :         ancestors = get_partition_ancestors(relid);
     220        1570 :         ancestors = lcons_oid(relid, ancestors);
     221             : 
     222             :         /* The only state we need is the ancestors list */
     223        1570 :         funcctx->user_fctx = (void *) ancestors;
     224             : 
     225        1570 :         MemoryContextSwitchTo(oldcxt);
     226             :     }
     227             : 
     228        4066 :     funcctx = SRF_PERCALL_SETUP();
     229        4066 :     ancestors = (List *) funcctx->user_fctx;
     230             : 
     231        4066 :     if (funcctx->call_cntr < list_length(ancestors))
     232             :     {
     233        2496 :         Oid         resultrel = list_nth_oid(ancestors, funcctx->call_cntr);
     234             : 
     235        2496 :         SRF_RETURN_NEXT(funcctx, ObjectIdGetDatum(resultrel));
     236             :     }
     237             : 
     238        1570 :     SRF_RETURN_DONE(funcctx);
     239             : }