greenplumn hashutil 源码
greenplumn hashutil 代码
文件路径：/src/backend/access/hash/hashutil.c
/*-------------------------------------------------------------------------
*
* hashutil.c
* Utility code for Postgres hash implementation.
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/hash/hashutil.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/hash.h"
#include "access/reloptions.h"
#include "access/relscan.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "storage/buf_internals.h"
#define CALC_NEW_BUCKET(old_bucket, lowmask) \
old_bucket | (lowmask + 1)
/*
* _hash_checkqual -- does the index tuple satisfy the scan conditions?
*/
bool
_hash_checkqual(IndexScanDesc scan, IndexTuple itup)
{
/*
* Currently, we can't check any of the scan conditions since we do not
* have the original index entry value to supply to the sk_func. Always
* return true; we expect that hashgettuple already set the recheck flag
* to make the main indexscan code do it.
*/
#ifdef NOT_USED
TupleDesc tupdesc = RelationGetDescr(scan->indexRelation);
ScanKey key = scan->keyData;
int scanKeySize = scan->numberOfKeys;
while (scanKeySize > 0)
{
Datum datum;
bool isNull;
Datum test;
datum = index_getattr(itup,
key->sk_attno,
tupdesc,
&isNull);
/* assume sk_func is strict */
if (isNull)
return false;
if (key->sk_flags & SK_ISNULL)
return false;
test = FunctionCall2Coll(&key->sk_func, key->sk_collation,
datum, key->sk_argument);
if (!DatumGetBool(test))
return false;
key++;
scanKeySize--;
}
#endif
return true;
}
/*
* _hash_datum2hashkey -- given a Datum, call the index's hash function
*
* The Datum is assumed to be of the index's column type, so we can use the
* "primary" hash function that's tracked for us by the generic index code.
*/
uint32
_hash_datum2hashkey(Relation rel, Datum key)
{
FmgrInfo *procinfo;
Oid collation;
/* XXX assumes index has only one attribute */
procinfo = index_getprocinfo(rel, 1, HASHSTANDARD_PROC);
collation = rel->rd_indcollation[0];
return DatumGetUInt32(FunctionCall1Coll(procinfo, collation, key));
}
/*
* _hash_datum2hashkey_type -- given a Datum of a specified type,
* hash it in a fashion compatible with this index
*
* This is much more expensive than _hash_datum2hashkey, so use it only in
* cross-type situations.
*/
uint32
_hash_datum2hashkey_type(Relation rel, Datum key, Oid keytype)
{
RegProcedure hash_proc;
Oid collation;
/* XXX assumes index has only one attribute */
hash_proc = get_opfamily_proc(rel->rd_opfamily[0],
keytype,
keytype,
HASHSTANDARD_PROC);
if (!RegProcedureIsValid(hash_proc))
elog(ERROR, "missing support function %d(%u,%u) for index \"%s\"",
HASHSTANDARD_PROC, keytype, keytype,
RelationGetRelationName(rel));
collation = rel->rd_indcollation[0];
return DatumGetUInt32(OidFunctionCall1Coll(hash_proc, collation, key));
}
/*
* _hash_hashkey2bucket -- determine which bucket the hashkey maps to.
*/
Bucket
_hash_hashkey2bucket(uint32 hashkey, uint32 maxbucket,
uint32 highmask, uint32 lowmask)
{
Bucket bucket;
bucket = hashkey & highmask;
if (bucket > maxbucket)
bucket = bucket & lowmask;
return bucket;
}
/*
* _hash_log2 -- returns ceil(lg2(num))
*/
uint32
_hash_log2(uint32 num)
{
uint32 i,
limit;
limit = 1;
for (i = 0; limit < num; limit <<= 1, i++)
;
return i;
}
/*
* _hash_spareindex -- returns spare index / global splitpoint phase of the
* bucket
*/
uint32
_hash_spareindex(uint32 num_bucket)
{
uint32 splitpoint_group;
uint32 splitpoint_phases;
splitpoint_group = _hash_log2(num_bucket);
if (splitpoint_group < HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE)
return splitpoint_group;
/* account for single-phase groups */
splitpoint_phases = HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE;
/* account for multi-phase groups before splitpoint_group */
splitpoint_phases +=
((splitpoint_group - HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE) <<
HASH_SPLITPOINT_PHASE_BITS);
/* account for phases within current group */
splitpoint_phases +=
(((num_bucket - 1) >>
(splitpoint_group - (HASH_SPLITPOINT_PHASE_BITS + 1))) &
HASH_SPLITPOINT_PHASE_MASK); /* to 0-based value. */
return splitpoint_phases;
}
/*
* _hash_get_totalbuckets -- returns total number of buckets allocated till
* the given splitpoint phase.
*/
uint32
_hash_get_totalbuckets(uint32 splitpoint_phase)
{
uint32 splitpoint_group;
uint32 total_buckets;
uint32 phases_within_splitpoint_group;
if (splitpoint_phase < HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE)
return (1 << splitpoint_phase);
/* get splitpoint's group */
splitpoint_group = HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE;
splitpoint_group +=
((splitpoint_phase - HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE) >>
HASH_SPLITPOINT_PHASE_BITS);
/* account for buckets before splitpoint_group */
total_buckets = (1 << (splitpoint_group - 1));
/* account for buckets within splitpoint_group */
phases_within_splitpoint_group =
(((splitpoint_phase - HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE) &
HASH_SPLITPOINT_PHASE_MASK) + 1); /* from 0-based to 1-based */
total_buckets +=
(((1 << (splitpoint_group - 1)) >> HASH_SPLITPOINT_PHASE_BITS) *
phases_within_splitpoint_group);
return total_buckets;
}
/*
* _hash_checkpage -- sanity checks on the format of all hash pages
*
* If flags is not zero, it is a bitwise OR of the acceptable page types
* (values of hasho_flag & LH_PAGE_TYPE).
*/
void
_hash_checkpage(Relation rel, Buffer buf, int flags)
{
Page page = BufferGetPage(buf);
/*
* ReadBuffer verifies that every newly-read page passes
* PageHeaderIsValid, which means it either contains a reasonably sane
* page header or is all-zero. We have to defend against the all-zero
* case, however.
*/
if (PageIsNew(page))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains unexpected zero page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
/*
* Additionally check that the special area looks sane.
*/
if (PageGetSpecialSize(page) != MAXALIGN(sizeof(HashPageOpaqueData)))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
if (flags)
{
HashPageOpaque opaque = (HashPageOpaque) PageGetSpecialPointer(page);
if ((opaque->hasho_flag & flags) == 0)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
}
/*
* When checking the metapage, also verify magic number and version.
*/
if (flags == LH_META_PAGE)
{
HashMetaPage metap = HashPageGetMeta(page);
if (metap->hashm_magic != HASH_MAGIC)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" is not a hash index",
RelationGetRelationName(rel))));
if (metap->hashm_version != HASH_VERSION)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" has wrong hash version",
RelationGetRelationName(rel)),
errhint("Please REINDEX it.")));
}
}
bytea *
hashoptions(Datum reloptions, bool validate)
{
return default_reloptions(reloptions, validate, RELOPT_KIND_HASH);
}
/*
* _hash_get_indextuple_hashkey - get the hash index tuple's hash key value
*/
uint32
_hash_get_indextuple_hashkey(IndexTuple itup)
{
char *attp;
/*
* We assume the hash key is the first attribute and can't be null, so
* this can be done crudely but very very cheaply ...
*/
attp = (char *) itup + IndexInfoFindDataOffset(itup->t_info);
return *((uint32 *) attp);
}
/*
* _hash_convert_tuple - convert raw index data to hash key
*
* Inputs: values and isnull arrays for the user data column(s)
* Outputs: values and isnull arrays for the index tuple, suitable for
* passing to index_form_tuple().
*
* Returns true if successful, false if not (because there are null values).
* On a false result, the given data need not be indexed.
*
* Note: callers know that the index-column arrays are always of length 1.
* In principle, there could be more than one input column, though we do not
* currently support that.
*/
bool
_hash_convert_tuple(Relation index,
Datum *user_values, bool *user_isnull,
Datum *index_values, bool *index_isnull)
{
uint32 hashkey;
/*
* We do not insert null values into hash indexes. This is okay because
* the only supported search operator is '=', and we assume it is strict.
*/
if (user_isnull[0])
return false;
hashkey = _hash_datum2hashkey(index, user_values[0]);
index_values[0] = UInt32GetDatum(hashkey);
index_isnull[0] = false;
return true;
}
/*
* _hash_binsearch - Return the offset number in the page where the
* specified hash value should be sought or inserted.
*
* We use binary search, relying on the assumption that the existing entries
* are ordered by hash key.
*
* Returns the offset of the first index entry having hashkey >= hash_value,
* or the page's max offset plus one if hash_value is greater than all
* existing hash keys in the page. This is the appropriate place to start
* a search, or to insert a new item.
*/
OffsetNumber
_hash_binsearch(Page page, uint32 hash_value)
{
OffsetNumber upper;
OffsetNumber lower;
/* Loop invariant: lower <= desired place <= upper */
upper = PageGetMaxOffsetNumber(page) + 1;
lower = FirstOffsetNumber;
while (upper > lower)
{
OffsetNumber off;
IndexTuple itup;
uint32 hashkey;
off = (upper + lower) / 2;
Assert(OffsetNumberIsValid(off));
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, off));
hashkey = _hash_get_indextuple_hashkey(itup);
if (hashkey < hash_value)
lower = off + 1;
else
upper = off;
}
return lower;
}
/*
* _hash_binsearch_last
*
* Same as above, except that if there are multiple matching items in the
* page, we return the offset of the last one instead of the first one,
* and the possible range of outputs is 0..maxoffset not 1..maxoffset+1.
* This is handy for starting a new page in a backwards scan.
*/
OffsetNumber
_hash_binsearch_last(Page page, uint32 hash_value)
{
OffsetNumber upper;
OffsetNumber lower;
/* Loop invariant: lower <= desired place <= upper */
upper = PageGetMaxOffsetNumber(page);
lower = FirstOffsetNumber - 1;
while (upper > lower)
{
IndexTuple itup;
OffsetNumber off;
uint32 hashkey;
off = (upper + lower + 1) / 2;
Assert(OffsetNumberIsValid(off));
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, off));
hashkey = _hash_get_indextuple_hashkey(itup);
if (hashkey > hash_value)
upper = off - 1;
else
lower = off;
}
return lower;
}
/*
* _hash_get_oldblock_from_newbucket() -- get the block number of a bucket
* from which current (new) bucket is being split.
*/
BlockNumber
_hash_get_oldblock_from_newbucket(Relation rel, Bucket new_bucket)
{
Bucket old_bucket;
uint32 mask;
Buffer metabuf;
HashMetaPage metap;
BlockNumber blkno;
/*
* To get the old bucket from the current bucket, we need a mask to modulo
* into lower half of table. This mask is stored in meta page as
* hashm_lowmask, but here we can't rely on the same, because we need a
* value of lowmask that was prevalent at the time when bucket split was
* started. Masking the most significant bit of new bucket would give us
* old bucket.
*/
mask = (((uint32) 1) << (fls(new_bucket) - 1)) - 1;
old_bucket = new_bucket & mask;
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
metap = HashPageGetMeta(BufferGetPage(metabuf));
blkno = BUCKET_TO_BLKNO(metap, old_bucket);
_hash_relbuf(rel, metabuf);
return blkno;
}
/*
* _hash_get_newblock_from_oldbucket() -- get the block number of a bucket
* that will be generated after split from old bucket.
*
* This is used to find the new bucket from old bucket based on current table
* half. It is mainly required to finish the incomplete splits where we are
* sure that not more than one bucket could have split in progress from old
* bucket.
*/
BlockNumber
_hash_get_newblock_from_oldbucket(Relation rel, Bucket old_bucket)
{
Bucket new_bucket;
Buffer metabuf;
HashMetaPage metap;
BlockNumber blkno;
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
metap = HashPageGetMeta(BufferGetPage(metabuf));
new_bucket = _hash_get_newbucket_from_oldbucket(rel, old_bucket,
metap->hashm_lowmask,
metap->hashm_maxbucket);
blkno = BUCKET_TO_BLKNO(metap, new_bucket);
_hash_relbuf(rel, metabuf);
return blkno;
}
/*
* _hash_get_newbucket_from_oldbucket() -- get the new bucket that will be
* generated after split from current (old) bucket.
*
* This is used to find the new bucket from old bucket. New bucket can be
* obtained by OR'ing old bucket with most significant bit of current table
* half (lowmask passed in this function can be used to identify msb of
* current table half). There could be multiple buckets that could have
* been split from current bucket. We need the first such bucket that exists.
* Caller must ensure that no more than one split has happened from old
* bucket.
*/
Bucket
_hash_get_newbucket_from_oldbucket(Relation rel, Bucket old_bucket,
uint32 lowmask, uint32 maxbucket)
{
Bucket new_bucket;
new_bucket = CALC_NEW_BUCKET(old_bucket, lowmask);
if (new_bucket > maxbucket)
{
lowmask = lowmask >> 1;
new_bucket = CALC_NEW_BUCKET(old_bucket, lowmask);
}
return new_bucket;
}
/*
* _hash_kill_items - set LP_DEAD state for items an indexscan caller has
* told us were killed.
*
* scan->opaque, referenced locally through so, contains information about the
* current page and killed tuples thereon (generally, this should only be
* called if so->numKilled > 0).
*
* The caller does not have a lock on the page and may or may not have the
* page pinned in a buffer. Note that read-lock is sufficient for setting
* LP_DEAD status (which is only a hint).
*
* The caller must have pin on bucket buffer, but may or may not have pin
* on overflow buffer, as indicated by HashScanPosIsPinned(so->currPos).
*
* We match items by heap TID before assuming they are the right ones to
* delete.
*
* There are never any scans active in a bucket at the time VACUUM begins,
* because VACUUM takes a cleanup lock on the primary bucket page and scans
* hold a pin. A scan can begin after VACUUM leaves the primary bucket page
* but before it finishes the entire bucket, but it can never pass VACUUM,
* because VACUUM always locks the next page before releasing the lock on
* the previous one. Therefore, we don't have to worry about accidentally
* killing a TID that has been reused for an unrelated tuple.
*/
void
_hash_kill_items(IndexScanDesc scan)
{
HashScanOpaque so = (HashScanOpaque) scan->opaque;
Relation rel = scan->indexRelation;
BlockNumber blkno;
Buffer buf;
Page page;
HashPageOpaque opaque;
OffsetNumber offnum,
maxoff;
int numKilled = so->numKilled;
int i;
bool killedsomething = false;
bool havePin = false;
Assert(so->numKilled > 0);
Assert(so->killedItems != NULL);
Assert(HashScanPosIsValid(so->currPos));
/*
* Always reset the scan state, so we don't look for same items on other
* pages.
*/
so->numKilled = 0;
blkno = so->currPos.currPage;
if (HashScanPosIsPinned(so->currPos))
{
/*
* We already have pin on this buffer, so, all we need to do is
* acquire lock on it.
*/
havePin = true;
buf = so->currPos.buf;
LockBuffer(buf, BUFFER_LOCK_SHARE);
}
else
buf = _hash_getbuf(rel, blkno, HASH_READ, LH_OVERFLOW_PAGE);
page = BufferGetPage(buf);
opaque = (HashPageOpaque) PageGetSpecialPointer(page);
maxoff = PageGetMaxOffsetNumber(page);
for (i = 0; i < numKilled; i++)
{
int itemIndex = so->killedItems[i];
HashScanPosItem *currItem = &so->currPos.items[itemIndex];
offnum = currItem->indexOffset;
Assert(itemIndex >= so->currPos.firstItem &&
itemIndex <= so->currPos.lastItem);
while (offnum <= maxoff)
{
ItemId iid = PageGetItemId(page, offnum);
IndexTuple ituple = (IndexTuple) PageGetItem(page, iid);
if (ItemPointerEquals(&ituple->t_tid, &currItem->heapTid))
{
/* found the item */
ItemIdMarkDead(iid);
killedsomething = true;
break; /* out of inner search loop */
}
offnum = OffsetNumberNext(offnum);
}
}
/*
* Since this can be redone later if needed, mark as dirty hint. Whenever
* we mark anything LP_DEAD, we also set the page's
* LH_PAGE_HAS_DEAD_TUPLES flag, which is likewise just a hint.
*/
if (killedsomething)
{
opaque->hasho_flag |= LH_PAGE_HAS_DEAD_TUPLES;
MarkBufferDirtyHint(buf, true);
}
if (so->hashso_bucket_buf == so->currPos.buf ||
havePin)
LockBuffer(so->currPos.buf, BUFFER_LOCK_UNLOCK);
else
_hash_relbuf(rel, buf);
}
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