attoptcache.h File Reference

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Data Structures
struct	AttributeOpts

Typedefs
typedef struct AttributeOpts	AttributeOpts

Functions
AttributeOpts *	get_attribute_options (Oid attrelid, int attnum)

Typedef Documentation

AttributeOpts

typedef struct AttributeOpts AttributeOpts

Function Documentation

get_attribute_options()

AttributeOpts * get_attribute_options ( Oid  attrelid, int  attnum  )

extern

Definition at line 131 of file attoptcache.c.

{
    AttoptCacheKey key;
    AttoptCacheEntry *attopt;
    AttributeOpts *result;
    HeapTuple   tp;
 
    /* Find existing cache entry, if any. */
    if (!AttoptCacheHash)
        InitializeAttoptCache();
    memset(&key, 0, sizeof(key));   /* make sure any padding bits are unset */
    key.attrelid = attrelid;
    key.attnum = attnum;
    attopt =
        (AttoptCacheEntry *) hash_search(AttoptCacheHash,
                                         &key,
                                         HASH_FIND,
                                         NULL);
 
    /* Not found in Attopt cache.  Construct new cache entry. */
    if (!attopt)
    {
        AttributeOpts *opts;
 
        tp = SearchSysCache2(ATTNUM,
                             ObjectIdGetDatum(attrelid),
                             Int16GetDatum(attnum));
 
        /*
         * If we don't find a valid HeapTuple, it must mean someone has
         * managed to request attribute details for a non-existent attribute.
         * We treat that case as if no options were specified.
         */
        if (!HeapTupleIsValid(tp))
            opts = NULL;
        else
        {
            Datum       datum;
            bool        isNull;
 
            datum = SysCacheGetAttr(ATTNUM,
                                    tp,
                                    Anum_pg_attribute_attoptions,
                                    &isNull);
            if (isNull)
                opts = NULL;
            else
            {
                bytea      *bytea_opts = attribute_reloptions(datum, false);
 
                opts = MemoryContextAlloc(CacheMemoryContext,
                                          VARSIZE(bytea_opts));
                memcpy(opts, bytea_opts, VARSIZE(bytea_opts));
            }
            ReleaseSysCache(tp);
        }
 
        /*
         * It's important to create the actual cache entry only after reading
         * pg_attribute, since the read could cause a cache flush.
         */
        attopt = (AttoptCacheEntry *) hash_search(AttoptCacheHash,
                                                  &key,
                                                  HASH_ENTER,
                                                  NULL);
        attopt->opts = opts;
    }
 
    /* Return results in caller's memory context. */
    if (attopt->opts == NULL)
        return NULL;
    result = palloc(VARSIZE(attopt->opts));
    memcpy(result, attopt->opts, VARSIZE(attopt->opts));
    return result;
}

References attnum, AttoptCacheHash, attribute_reloptions(), CacheMemoryContext, fb(), HASH_ENTER, HASH_FIND, hash_search(), HeapTupleIsValid, InitializeAttoptCache(), Int16GetDatum(), MemoryContextAlloc(), ObjectIdGetDatum(), opts, palloc(), ReleaseSysCache(), SearchSysCache2(), SysCacheGetAttr(), and VARSIZE().

Referenced by compute_expr_stats(), and do_analyze_rel().