|
| 1 | +/*---------------------------------------------------------------------- |
| 2 | + * |
| 3 | + * tableamapi.c |
| 4 | + *Support routines for API for Postgres table access methods |
| 5 | + * |
| 6 | + * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group |
| 7 | + * Portions Copyright (c) 1994, Regents of the University of California |
| 8 | + * |
| 9 | + * src/backend/access/table/tableamapi.c |
| 10 | + *---------------------------------------------------------------------- |
| 11 | + */ |
| 12 | +#include"postgres.h" |
| 13 | + |
| 14 | +#include"access/heapam.h" |
| 15 | +#include"access/htup_details.h" |
| 16 | +#include"access/tableam.h" |
| 17 | +#include"access/xact.h" |
| 18 | +#include"catalog/pg_am.h" |
| 19 | +#include"catalog/pg_proc.h" |
| 20 | +#include"utils/fmgroids.h" |
| 21 | +#include"utils/memutils.h" |
| 22 | +#include"utils/syscache.h" |
| 23 | + |
| 24 | + |
| 25 | +staticOidget_table_am_oid(constchar*tableamname,boolmissing_ok); |
| 26 | + |
| 27 | + |
| 28 | +/* |
| 29 | + * GetTableAmRoutine |
| 30 | + *Call the specified access method handler routine to get its |
| 31 | + *TableAmRoutine struct, which will be palloc'd in the caller's |
| 32 | + *memory context. |
| 33 | + */ |
| 34 | +constTableAmRoutine* |
| 35 | +GetTableAmRoutine(Oidamhandler) |
| 36 | +{ |
| 37 | +Datumdatum; |
| 38 | +constTableAmRoutine*routine; |
| 39 | + |
| 40 | +datum=OidFunctionCall0(amhandler); |
| 41 | +routine= (TableAmRoutine*)DatumGetPointer(datum); |
| 42 | + |
| 43 | +if (routine==NULL|| !IsA(routine,TableAmRoutine)) |
| 44 | +elog(ERROR,"Table access method handler %u did not return a TableAmRoutine struct", |
| 45 | +amhandler); |
| 46 | + |
| 47 | +returnroutine; |
| 48 | +} |
| 49 | + |
| 50 | +/* |
| 51 | + * GetTableAmRoutineByAmId - look up the handler of the table access |
| 52 | + * method with the given OID, and get its TableAmRoutine struct. |
| 53 | + */ |
| 54 | +constTableAmRoutine* |
| 55 | +GetTableAmRoutineByAmId(Oidamoid) |
| 56 | +{ |
| 57 | +regprocamhandler; |
| 58 | +HeapTupletuple; |
| 59 | +Form_pg_amamform; |
| 60 | + |
| 61 | +/* Get handler function OID for the access method */ |
| 62 | +tuple=SearchSysCache1(AMOID,ObjectIdGetDatum(amoid)); |
| 63 | +if (!HeapTupleIsValid(tuple)) |
| 64 | +elog(ERROR,"cache lookup failed for access method %u", |
| 65 | +amoid); |
| 66 | +amform= (Form_pg_am)GETSTRUCT(tuple); |
| 67 | + |
| 68 | +/* Check that it is a table access method */ |
| 69 | +if (amform->amtype!=AMTYPE_TABLE) |
| 70 | +ereport(ERROR, |
| 71 | +(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), |
| 72 | +errmsg("access method \"%s\" is not of type %s", |
| 73 | +NameStr(amform->amname),"TABLE"))); |
| 74 | + |
| 75 | +amhandler=amform->amhandler; |
| 76 | + |
| 77 | +/* Complain if handler OID is invalid */ |
| 78 | +if (!RegProcedureIsValid(amhandler)) |
| 79 | +ereport(ERROR, |
| 80 | +(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), |
| 81 | +errmsg("table access method \"%s\" does not have a handler", |
| 82 | +NameStr(amform->amname)))); |
| 83 | + |
| 84 | +ReleaseSysCache(tuple); |
| 85 | + |
| 86 | +/* And finally, call the handler function to get the API struct. */ |
| 87 | +returnGetTableAmRoutine(amhandler); |
| 88 | +} |
| 89 | + |
| 90 | +/* |
| 91 | + * get_table_am_oid - given a table access method name, look up the OID |
| 92 | + * |
| 93 | + * If missing_ok is false, throw an error if table access method name not |
| 94 | + * found. If true, just return InvalidOid. |
| 95 | + */ |
| 96 | +staticOid |
| 97 | +get_table_am_oid(constchar*tableamname,boolmissing_ok) |
| 98 | +{ |
| 99 | +Oidresult; |
| 100 | +Relationrel; |
| 101 | +HeapScanDescscandesc; |
| 102 | +HeapTupletuple; |
| 103 | +ScanKeyDataentry[1]; |
| 104 | + |
| 105 | +/* |
| 106 | + * Search pg_tablespace. We use a heapscan here even though there is an |
| 107 | + * index on name, on the theory that pg_tablespace will usually have just |
| 108 | + * a few entries and so an indexed lookup is a waste of effort. |
| 109 | + */ |
| 110 | +rel=heap_open(AccessMethodRelationId,AccessShareLock); |
| 111 | + |
| 112 | +ScanKeyInit(&entry[0], |
| 113 | +Anum_pg_am_amname, |
| 114 | +BTEqualStrategyNumber,F_NAMEEQ, |
| 115 | +CStringGetDatum(tableamname)); |
| 116 | +scandesc=heap_beginscan_catalog(rel,1,entry); |
| 117 | +tuple=heap_getnext(scandesc,ForwardScanDirection); |
| 118 | + |
| 119 | +/* We assume that there can be at most one matching tuple */ |
| 120 | +if (HeapTupleIsValid(tuple)&& |
| 121 | +((Form_pg_am)GETSTRUCT(tuple))->amtype==AMTYPE_TABLE) |
| 122 | +result= ((Form_pg_am)GETSTRUCT(tuple))->oid; |
| 123 | +else |
| 124 | +result=InvalidOid; |
| 125 | + |
| 126 | +heap_endscan(scandesc); |
| 127 | +heap_close(rel,AccessShareLock); |
| 128 | + |
| 129 | +if (!OidIsValid(result)&& !missing_ok) |
| 130 | +ereport(ERROR, |
| 131 | +(errcode(ERRCODE_UNDEFINED_OBJECT), |
| 132 | +errmsg("table access method \"%s\" does not exist", |
| 133 | +tableamname))); |
| 134 | + |
| 135 | +returnresult; |
| 136 | +} |
| 137 | + |
| 138 | +/* check_hook: validate new default_table_access_method */ |
| 139 | +bool |
| 140 | +check_default_table_access_method(char**newval,void**extra,GucSourcesource) |
| 141 | +{ |
| 142 | +/* |
| 143 | + * If we aren't inside a transaction, we cannot do database access so |
| 144 | + * cannot verify the name. Must accept the value on faith. |
| 145 | + */ |
| 146 | +if (IsTransactionState()) |
| 147 | +{ |
| 148 | +if (**newval!='\0'&& |
| 149 | +!OidIsValid(get_table_am_oid(*newval, true))) |
| 150 | +{ |
| 151 | +/* |
| 152 | + * When source == PGC_S_TEST, don't throw a hard error for a |
| 153 | + * nonexistent table access method, only a NOTICE. See comments in |
| 154 | + * guc.h. |
| 155 | + */ |
| 156 | +if (source==PGC_S_TEST) |
| 157 | +{ |
| 158 | +ereport(NOTICE, |
| 159 | +(errcode(ERRCODE_UNDEFINED_OBJECT), |
| 160 | +errmsg("Table access method \"%s\" does not exist", |
| 161 | +*newval))); |
| 162 | +} |
| 163 | +else |
| 164 | +{ |
| 165 | +GUC_check_errdetail("Table access method \"%s\" does not exist.", |
| 166 | +*newval); |
| 167 | +return false; |
| 168 | +} |
| 169 | +} |
| 170 | +} |
| 171 | + |
| 172 | +return true; |
| 173 | +} |