dummy_index_am.c

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/*-------------------------------------------------------------------------
 *
 * dummy_index_am.c
 *      Index AM template main file.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/test/modules/dummy_index_am/dummy_index_am.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/amapi.h"
#include "access/reloptions.h"
#include "catalog/index.h"
#include "commands/vacuum.h"
#include "nodes/pathnodes.h"
 
PG_MODULE_MAGIC;
 
/* parse table for fillRelOptions */
static relopt_parse_elt di_relopt_tab[6];
 
/* Kind of relation options for dummy index */
static relopt_kind di_relopt_kind;
 
typedef enum DummyAmEnum
{
    DUMMY_AM_ENUM_ONE,
    DUMMY_AM_ENUM_TWO,
}           DummyAmEnum;
 
/* Dummy index options */
typedef struct DummyIndexOptions
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    int         option_int;
    double      option_real;
    bool        option_bool;
    DummyAmEnum option_enum;
    int         option_string_val_offset;
    int         option_string_null_offset;
}           DummyIndexOptions;
 
static relopt_enum_elt_def dummyAmEnumValues[] =
{
    {"one", DUMMY_AM_ENUM_ONE},
    {"two", DUMMY_AM_ENUM_TWO},
    {(const char *) NULL}       /* list terminator */
};
 
/* Handler for index AM */
PG_FUNCTION_INFO_V1(dihandler);
 
/*
 * Validation function for string relation options.
 */
static void
validate_string_option(const char *value)
{
    ereport(NOTICE,
            (errmsg("new option value for string parameter %s",
                    value ? value : "NULL")));
}
 
/*
 * This function creates a full set of relation option types,
 * with various patterns.
 */
static void
create_reloptions_table(void)
{
    di_relopt_kind = add_reloption_kind();
 
    add_int_reloption(di_relopt_kind, "option_int",
                      "Integer option for dummy_index_am",
                      10, -10, 100, AccessExclusiveLock);
    di_relopt_tab[0].optname = "option_int";
    di_relopt_tab[0].opttype = RELOPT_TYPE_INT;
    di_relopt_tab[0].offset = offsetof(DummyIndexOptions, option_int);
 
    add_real_reloption(di_relopt_kind, "option_real",
                       "Real option for dummy_index_am",
                       3.1415, -10, 100, AccessExclusiveLock);
    di_relopt_tab[1].optname = "option_real";
    di_relopt_tab[1].opttype = RELOPT_TYPE_REAL;
    di_relopt_tab[1].offset = offsetof(DummyIndexOptions, option_real);
 
    add_bool_reloption(di_relopt_kind, "option_bool",
                       "Boolean option for dummy_index_am",
                       true, AccessExclusiveLock);
    di_relopt_tab[2].optname = "option_bool";
    di_relopt_tab[2].opttype = RELOPT_TYPE_BOOL;
    di_relopt_tab[2].offset = offsetof(DummyIndexOptions, option_bool);
 
    add_enum_reloption(di_relopt_kind, "option_enum",
                       "Enum option for dummy_index_am",
                       dummyAmEnumValues,
                       DUMMY_AM_ENUM_ONE,
                       "Valid values are \"one\" and \"two\".",
                       AccessExclusiveLock);
    di_relopt_tab[3].optname = "option_enum";
    di_relopt_tab[3].opttype = RELOPT_TYPE_ENUM;
    di_relopt_tab[3].offset = offsetof(DummyIndexOptions, option_enum);
 
    add_string_reloption(di_relopt_kind, "option_string_val",
                         "String option for dummy_index_am with non-NULL default",
                         "DefaultValue", &validate_string_option,
                         AccessExclusiveLock);
    di_relopt_tab[4].optname = "option_string_val";
    di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
    di_relopt_tab[4].offset = offsetof(DummyIndexOptions,
                                       option_string_val_offset);
 
    /*
     * String option for dummy_index_am with NULL default, and without
     * description.
     */
    add_string_reloption(di_relopt_kind, "option_string_null",
                         NULL,  /* description */
                         NULL, &validate_string_option,
                         AccessExclusiveLock);
    di_relopt_tab[5].optname = "option_string_null";
    di_relopt_tab[5].opttype = RELOPT_TYPE_STRING;
    di_relopt_tab[5].offset = offsetof(DummyIndexOptions,
                                       option_string_null_offset);
}
 
 
/*
 * Build a new index.
 */
static IndexBuildResult *
dibuild(Relation heap, Relation index, IndexInfo *indexInfo)
{
    IndexBuildResult *result;
 
    result = palloc_object(IndexBuildResult);
 
    /* let's pretend that no tuples were scanned */
    result->heap_tuples = 0;
    /* and no index tuples were created (that is true) */
    result->index_tuples = 0;
 
    return result;
}
 
/*
 * Build an empty index for the initialization fork.
 */
static void
dibuildempty(Relation index)
{
    /* No need to build an init fork for a dummy index */
}
 
/*
 * Insert new tuple to index AM.
 */
static bool
diinsert(Relation index, Datum *values, bool *isnull,
         ItemPointer ht_ctid, Relation heapRel,
         IndexUniqueCheck checkUnique,
         bool indexUnchanged,
         IndexInfo *indexInfo)
{
    /* nothing to do */
    return false;
}
 
/*
 * Bulk deletion of all index entries pointing to a set of table tuples.
 */
static IndexBulkDeleteResult *
dibulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
             IndexBulkDeleteCallback callback, void *callback_state)
{
    /*
     * There is nothing to delete.  Return NULL as there is nothing to pass to
     * amvacuumcleanup.
     */
    return NULL;
}
 
/*
 * Post-VACUUM cleanup for index AM.
 */
static IndexBulkDeleteResult *
divacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
{
    /* Index has not been modified, so returning NULL is fine */
    return NULL;
}
 
/*
 * Estimate cost of index AM.
 */
static void
dicostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
               Cost *indexStartupCost, Cost *indexTotalCost,
               Selectivity *indexSelectivity, double *indexCorrelation,
               double *indexPages)
{
    /* Tell planner to never use this index! */
    *indexStartupCost = 1.0e10;
    *indexTotalCost = 1.0e10;
 
    /* Do not care about the rest */
    *indexSelectivity = 1;
    *indexCorrelation = 0;
    *indexPages = 1;
}
 
/*
 * Parse relation options for index AM, returning a DummyIndexOptions
 * structure filled with option values.
 */
static bytea *
dioptions(Datum reloptions, bool validate)
{
    return (bytea *) build_reloptions(reloptions, validate,
                                      di_relopt_kind,
                                      sizeof(DummyIndexOptions),
                                      di_relopt_tab, lengthof(di_relopt_tab));
}
 
/*
 * Validator for index AM.
 */
static bool
divalidate(Oid opclassoid)
{
    /* Index is dummy so we are happy with any opclass */
    return true;
}
 
/*
 * Begin scan of index AM.
 */
static IndexScanDesc
dibeginscan(Relation r, int nkeys, int norderbys)
{
    IndexScanDesc scan;
 
    /* Let's pretend we are doing something */
    scan = RelationGetIndexScan(r, nkeys, norderbys);
    return scan;
}
 
/*
 * Rescan of index AM.
 */
static void
direscan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
         ScanKey orderbys, int norderbys)
{
    /* nothing to do */
}
 
/*
 * End scan of index AM.
 */
static void
diendscan(IndexScanDesc scan)
{
    /* nothing to do */
}
 
/*
 * Index AM handler function: returns IndexAmRoutine with access method
 * parameters and callbacks.
 */
Datum
dihandler(PG_FUNCTION_ARGS)
{
    static const IndexAmRoutine amroutine = {
        .type = T_IndexAmRoutine,
        .amstrategies = 0,
        .amsupport = 1,
        .amcanorder = false,
        .amcanorderbyop = false,
        .amcanhash = false,
        .amconsistentequality = false,
        .amconsistentordering = false,
        .amcanbackward = false,
        .amcanunique = false,
        .amcanmulticol = false,
        .amoptionalkey = false,
        .amsearcharray = false,
        .amsearchnulls = false,
        .amstorage = false,
        .amclusterable = false,
        .ampredlocks = false,
        .amcanparallel = false,
        .amcanbuildparallel = false,
        .amcaninclude = false,
        .amusemaintenanceworkmem = false,
        .amsummarizing = false,
        .amparallelvacuumoptions = VACUUM_OPTION_NO_PARALLEL,
        .amkeytype = InvalidOid,
 
        .ambuild = dibuild,
        .ambuildempty = dibuildempty,
        .aminsert = diinsert,
        .ambulkdelete = dibulkdelete,
        .amvacuumcleanup = divacuumcleanup,
        .amcanreturn = NULL,
        .amcostestimate = dicostestimate,
        .amgettreeheight = NULL,
        .amoptions = dioptions,
        .amproperty = NULL,
        .ambuildphasename = NULL,
        .amvalidate = divalidate,
        .ambeginscan = dibeginscan,
        .amrescan = direscan,
        .amgettuple = NULL,
        .amgetbitmap = NULL,
        .amendscan = diendscan,
        .ammarkpos = NULL,
        .amrestrpos = NULL,
        .amestimateparallelscan = NULL,
        .aminitparallelscan = NULL,
        .amparallelrescan = NULL,
    };
 
    PG_RETURN_POINTER(&amroutine);
}
 
void
_PG_init(void)
{
    create_reloptions_table();
}