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Israel Hsu 2022-08-09 21:51:55 +00:00
parent 7b9299a77f
commit 86e675b74f
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202
src/mongo/db/s/shard_key_index_util.cpp Normal file
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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/bson/simple_bsonelement_comparator.h"
#include "mongo/db/catalog/clustered_collection_util.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/s/shard_key_index_util.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kSharding
namespace mongo {
namespace {
boost::optional<ShardKeyIndex> _findShardKeyPrefixedIndex(
OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalog* indexCatalog,
const boost::optional<std::string>& excludeName,
const BSONObj& shardKey,
bool requireSingleKey,
std::string* errMsg = nullptr) {
if (collection->isClustered() &&
clustered_util::matchesClusterKey(shardKey, collection->getClusteredInfo())) {
auto clusteredIndexSpec = collection->getClusteredInfo()->getIndexSpec();
return ShardKeyIndex(clusteredIndexSpec);
}
const IndexDescriptor* best = nullptr;
auto indexIterator =
indexCatalog->getIndexIterator(opCtx, IndexCatalog::InclusionPolicy::kReady);
while (indexIterator->more()) {
auto indexEntry = indexIterator->next();
auto indexDescriptor = indexEntry->descriptor();
if (excludeName && indexDescriptor->indexName() == *excludeName) {
continue;
}
if (isCompatibleWithShardKey(
opCtx, collection, indexEntry, shardKey, requireSingleKey, errMsg)) {
if (!indexEntry->isMultikey(opCtx, collection)) {
return ShardKeyIndex(indexDescriptor);
}
best = indexDescriptor;
}
}
if (best != nullptr) {
return ShardKeyIndex(best);
}
return boost::none;
}
} // namespace
ShardKeyIndex::ShardKeyIndex(const IndexDescriptor* indexDescriptor)
: _indexDescriptor(indexDescriptor) {
tassert(6012300,
"The indexDescriptor for ShardKeyIndex(const IndexDescriptor* indexDescripto) must not "
"be a nullptr",
indexDescriptor != nullptr);
}
ShardKeyIndex::ShardKeyIndex(const ClusteredIndexSpec& clusteredIndexSpec)
: _indexDescriptor(nullptr),
_clusteredIndexKeyPattern(clusteredIndexSpec.getKey().getOwned()) {}
const BSONObj& ShardKeyIndex::keyPattern() const {
if (_indexDescriptor != nullptr) {
return _indexDescriptor->keyPattern();
}
return _clusteredIndexKeyPattern;
}
bool isCompatibleWithShardKey(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalogEntry* indexEntry,
const BSONObj& shardKey,
bool requireSingleKey,
std::string* errMsg) {
// Return a descriptive error for each index that shares a prefix with shardKey but
// cannot be used for sharding.
const int kErrorPartial = 0x01;
const int kErrorSparse = 0x02;
const int kErrorMultikey = 0x04;
const int kErrorCollation = 0x08;
const int kErrorNotPrefix = 0x10;
int reasons = 0;
auto desc = indexEntry->descriptor();
bool hasSimpleCollation = desc->collation().isEmpty();
if (desc->isPartial()) {
reasons |= kErrorPartial;
}
if (desc->isSparse()) {
reasons |= kErrorSparse;
}
if (!shardKey.isPrefixOf(desc->keyPattern(), SimpleBSONElementComparator::kInstance)) {
reasons |= kErrorNotPrefix;
}
if (reasons == 0) { // that is, not partial index, not sparse, and not prefix, then:
if (!indexEntry->isMultikey(opCtx, collection)) {
if (hasSimpleCollation) {
return true;
}
} else {
reasons |= kErrorMultikey;
}
if (!requireSingleKey && hasSimpleCollation) {
return true;
}
}
if (!hasSimpleCollation) {
reasons |= kErrorCollation;
}
if (errMsg && reasons != 0) {
std::string errors = "Index " + indexEntry->descriptor()->indexName() +
" cannot be used for sharding because:";
if (reasons & kErrorPartial) {
errors += " Index key is partial.";
}
if (reasons & kErrorSparse) {
errors += " Index key is sparse.";
}
if (reasons & kErrorMultikey) {
errors += " Index key is multikey.";
}
if (reasons & kErrorCollation) {
errors += " Index has a non-simple collation.";
}
if (reasons & kErrorNotPrefix) {
errors += " Shard key is not a prefix of index key.";
}
if (!errMsg->empty()) {
*errMsg += "\n";
}
*errMsg += errors;
}
return false;
}
bool isLastShardKeyIndex(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalog* indexCatalog,
const std::string& indexName,
const BSONObj& shardKey) {
return !_findShardKeyPrefixedIndex(
opCtx, collection, indexCatalog, indexName, shardKey, false /* requireSingleKey */)
.is_initialized();
}
boost::optional<ShardKeyIndex> findShardKeyPrefixedIndex(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalog* indexCatalog,
const BSONObj& shardKey,
bool requireSingleKey,
std::string* errMsg) {
return _findShardKeyPrefixedIndex(
opCtx, collection, indexCatalog, boost::none, shardKey, requireSingleKey, errMsg);
}
} // namespace mongo

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src/mongo/db/s/shard_key_index_util.h Normal file
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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/bson/bsonobj.h"
#include "mongo/db/catalog/clustered_collection_options_gen.h"
#include "mongo/db/catalog/index_catalog.h"
namespace mongo {
class Collection;
class CollectionPtr;
class IndexDescriptor;
class ShardKeyIndex {
public:
/**
* Wraps information pertaining to the 'index' used as the shard key.
*
* A clustered index is not tied to an IndexDescriptor whereas all other types of indexes
* are. Either the 'index' is a clustered index and '_clusteredIndexKeyPattern' is
* non-empty, or '_indexDescriptor' is non-null and a standard index exists.
*/
ShardKeyIndex(const IndexDescriptor* indexDescriptor);
ShardKeyIndex(const ClusteredIndexSpec& clusteredIndexSpec);
const BSONObj& keyPattern() const;
const IndexDescriptor* descriptor() const {
return _indexDescriptor;
}
private:
const IndexDescriptor* _indexDescriptor;
// Stores the keyPattern when the index is a clustered index and there is no
// IndexDescriptor. Empty otherwise.
BSONObj _clusteredIndexKeyPattern;
};
/**
* Returns true if the given index is compatible with the shard key pattern.
*
* If return value is false and errMsg is non-null, the reasons that the existing index is
* incompatible will be appended to errMsg.
*/
bool isCompatibleWithShardKey(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalogEntry* indexEntry,
const BSONObj& shardKey,
bool requireSingleKey,
std::string* errMsg = nullptr);
/**
* Returns an index suitable for shard key range scans if it exists.
*
* This index:
* - must be prefixed by 'shardKey', and
* - must not be a partial index.
* - must have the simple collation.
*
* If the parameter 'requireSingleKey' is true, then this index additionally must not be
* multi-key.
*/
boost::optional<ShardKeyIndex> findShardKeyPrefixedIndex(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalog* indexCatalog,
const BSONObj& shardKey,
bool requireSingleKey,
std::string* errMsg = nullptr);
/**
* Returns true if the given index name is the last remaining index that is compatible with the
* shard key index.
*/
bool isLastShardKeyIndex(OperationContext* opCtx,
const CollectionPtr& collection,
const IndexCatalog* indexCatalog,
const std::string& indexName,
const BSONObj& shardKey);
} // namespace mongo