/*
* Does a compression algorithm exist by the name of `compresstype'?
*/
bool
compresstype_is_valid(char *comptype)
{
NameData compname;
bool found = false;
compname = comptype_to_name(comptype);
found = (0 !=
caql_getcount(
NULL,
cql("SELECT COUNT(*) FROM pg_compression "
" WHERE compname = :1 ",
NameGetDatum(&compname))));
/*
* FIXME: This is a hack. Should implement related handlers and register
* in system tables instead. snappy handlers have already been implemented
* but not registerd in system tables (see comment in GetCompressionImplement()
* for details).
*/
if(!found)
{
if(strcmp(comptype, "snappy") == 0 || strcmp(comptype, "gzip") == 0)
found = true;
}
return found;
}
/*
* Find the compression implementation (in pg_compression) for a particular
* compression type.
*
* Comparison is case insensitive.
*/
PGFunction *
GetCompressionImplementation(char *comptype)
{
HeapTuple tuple;
NameData compname;
PGFunction *funcs;
Form_pg_compression ctup;
FmgrInfo finfo;
Relation comprel;
ScanKeyData scankey;
SysScanDesc scan;
comprel = heap_open(CompressionRelationId, AccessShareLock);
compname = comptype_to_name(comptype);
/* SELECT * FROM pg_compression WHERE compname = :1 */
ScanKeyInit(&scankey,
Anum_pg_compression_compname,
BTEqualStrategyNumber, F_NAMEEQ,
NameGetDatum(&compname));
scan = systable_beginscan(comprel, CompressionCompnameIndexId, true,
SnapshotNow, 1, &scankey);
tuple = systable_getnext(scan);
if (!HeapTupleIsValid(tuple))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("unknown compress type \"%s\"",
comptype)));
funcs = palloc0(sizeof(PGFunction) * NUM_COMPRESS_FUNCS);
ctup = (Form_pg_compression)GETSTRUCT(tuple);
Insist(OidIsValid(ctup->compconstructor));
fmgr_info(ctup->compconstructor, &finfo);
funcs[COMPRESSION_CONSTRUCTOR] = finfo.fn_addr;
Insist(OidIsValid(ctup->compdestructor));
fmgr_info(ctup->compdestructor, &finfo);
funcs[COMPRESSION_DESTRUCTOR] = finfo.fn_addr;
Insist(OidIsValid(ctup->compcompressor));
fmgr_info(ctup->compcompressor, &finfo);
funcs[COMPRESSION_COMPRESS] = finfo.fn_addr;
Insist(OidIsValid(ctup->compdecompressor));
fmgr_info(ctup->compdecompressor, &finfo);
funcs[COMPRESSION_DECOMPRESS] = finfo.fn_addr;
Insist(OidIsValid(ctup->compvalidator));
fmgr_info(ctup->compvalidator, &finfo);
funcs[COMPRESSION_VALIDATOR] = finfo.fn_addr;
systable_endscan(scan);
heap_close(comprel, AccessShareLock);
return funcs;
}
/*
* Find the compression implementation (in pg_compression) for a particular
* compression type.
*
* Comparison is case insensitive.
*/
PGFunction *
GetCompressionImplementation(char *comptype)
{
HeapTuple tuple;
NameData compname;
PGFunction *funcs;
Form_pg_compression ctup;
FmgrInfo finfo;
compname = comptype_to_name(comptype);
/*
* This is a hack: We added the snappy support for row oriented storage, however
* to make the feature friendly to upgradation in short term, we decide to not
* modify the system table to implement this. Following ugly hack is to
* complete this. Let's remove this piece of code after snappy support is
* added to the related system tables.
*/
if (strcmp(NameStr(compname), "snappy") == 0)
{
funcs = palloc0(sizeof(PGFunction) * NUM_COMPRESS_FUNCS);
funcs[COMPRESSION_CONSTRUCTOR] = snappy_constructor;
funcs[COMPRESSION_DESTRUCTOR] = snappy_destructor;
funcs[COMPRESSION_COMPRESS] = snappy_compress_internal;
funcs[COMPRESSION_DECOMPRESS] = snappy_decompress_internal;
funcs[COMPRESSION_VALIDATOR] = snappy_validator;
return funcs;
}
tuple = caql_getfirst(
NULL,
cql("SELECT * FROM pg_compression "
" WHERE compname = :1 ",
NameGetDatum(&compname)));
if (!HeapTupleIsValid(tuple))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("unknown compress type \"%s\"",
comptype)));
funcs = palloc0(sizeof(PGFunction) * NUM_COMPRESS_FUNCS);
ctup = (Form_pg_compression)GETSTRUCT(tuple);
Insist(OidIsValid(ctup->compconstructor));
fmgr_info(ctup->compconstructor, &finfo);
funcs[COMPRESSION_CONSTRUCTOR] = finfo.fn_addr;
Insist(OidIsValid(ctup->compdestructor));
fmgr_info(ctup->compdestructor, &finfo);
funcs[COMPRESSION_DESTRUCTOR] = finfo.fn_addr;
Insist(OidIsValid(ctup->compcompressor));
fmgr_info(ctup->compcompressor, &finfo);
funcs[COMPRESSION_COMPRESS] = finfo.fn_addr;
Insist(OidIsValid(ctup->compdecompressor));
fmgr_info(ctup->compdecompressor, &finfo);
funcs[COMPRESSION_DECOMPRESS] = finfo.fn_addr;
Insist(OidIsValid(ctup->compvalidator));
fmgr_info(ctup->compvalidator, &finfo);
funcs[COMPRESSION_VALIDATOR] = finfo.fn_addr;
return funcs;
}
