/
sharding_catalog_manager_chunk_operations.cpp
1571 lines (1347 loc) · 70.5 KB
/
sharding_catalog_manager_chunk_operations.cpp
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/**
* Copyright (C) 2018-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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kSharding
#include "mongo/platform/basic.h"
#include "mongo/db/s/config/sharding_catalog_manager.h"
#include "mongo/base/status_with.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/bson/util/bson_extract.h"
#include "mongo/client/connection_string.h"
#include "mongo/client/read_preference.h"
#include "mongo/db/catalog_raii.h"
#include "mongo/db/dbdirectclient.h"
#include "mongo/db/logical_session_cache.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/query/distinct_command_gen.h"
#include "mongo/db/repl/repl_client_info.h"
#include "mongo/db/s/sharding_logging.h"
#include "mongo/db/s/sharding_util.h"
#include "mongo/db/server_options.h"
#include "mongo/db/snapshot_window_options_gen.h"
#include "mongo/db/transaction_participant_gen.h"
#include "mongo/logv2/log.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/s/balancer_configuration.h"
#include "mongo/s/catalog/sharding_catalog_client.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/client/shard.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/shard_key_pattern.h"
#include "mongo/s/shard_util.h"
#include "mongo/s/write_ops/batched_command_request.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/str.h"
namespace mongo {
namespace {
using FeatureCompatibilityParams = ServerGlobalParams::FeatureCompatibility;
MONGO_FAIL_POINT_DEFINE(migrationCommitVersionError);
MONGO_FAIL_POINT_DEFINE(migrateCommitInvalidChunkQuery);
MONGO_FAIL_POINT_DEFINE(skipExpiringOldChunkHistory);
const WriteConcernOptions kNoWaitWriteConcern(1, WriteConcernOptions::SyncMode::UNSET, Seconds(0));
/**
* Append min, max and version information from chunk to the buffer for logChange purposes.
*/
void appendShortVersion(BufBuilder* out, const ChunkType& chunk) {
BSONObjBuilder bb(*out);
bb.append(ChunkType::min(), chunk.getMin());
bb.append(ChunkType::max(), chunk.getMax());
if (chunk.isVersionSet()) {
chunk.getVersion().appendLegacyWithField(&bb, ChunkType::lastmod());
}
bb.done();
}
BSONArray buildMergeChunksTransactionUpdates(const std::vector<ChunkType>& chunksToMerge,
const ChunkVersion& mergeVersion,
const boost::optional<Timestamp>& validAfter) {
BSONArrayBuilder updates;
// Build an update operation to expand the first chunk into the newly merged chunk
{
BSONObjBuilder op;
op.append("op", "u");
op.appendBool("b", false); // no upsert
op.append("ns", ChunkType::ConfigNS.ns());
// expand first chunk into newly merged chunk
ChunkType mergedChunk(chunksToMerge.front());
mergedChunk.setMax(chunksToMerge.back().getMax());
// fill in additional details for sending through transaction
mergedChunk.setVersion(mergeVersion);
invariant(validAfter);
mergedChunk.setHistory({ChunkHistory(validAfter.get(), mergedChunk.getShard())});
// add the new chunk information as the update object
op.append("o", mergedChunk.toConfigBSON());
// query object
op.append("o2", BSON(ChunkType::name(mergedChunk.getName())));
updates.append(op.obj());
}
// Build update operations to delete the rest of the chunks to be merged. Remember not
// to delete the first chunk we're expanding
for (size_t i = 1; i < chunksToMerge.size(); ++i) {
BSONObjBuilder op;
op.append("op", "d");
op.append("ns", ChunkType::ConfigNS.ns());
op.append("o", BSON(ChunkType::name(chunksToMerge[i].getName())));
updates.append(op.obj());
}
return updates.arr();
}
BSONArray buildMergeChunksTransactionPrecond(const std::vector<ChunkType>& chunksToMerge,
const ChunkVersion& collVersion) {
BSONArrayBuilder preCond;
for (auto chunk : chunksToMerge) {
BSONObj query = BSON(ChunkType::min(chunk.getMin()) << ChunkType::max(chunk.getMax()));
if (collVersion.getTimestamp()) {
query = query.addFields(BSON(ChunkType::collectionUUID << chunk.getCollectionUUID()));
} else {
query = query.addFields(BSON(ChunkType::ns(chunk.getNS().ns())));
}
BSONObjBuilder b;
b.append("ns", ChunkType::ConfigNS.ns());
b.append("q", BSON("query" << query << "orderby" << BSON(ChunkType::lastmod() << -1)));
b.append("res",
BSON(ChunkType::epoch(collVersion.epoch())
<< ChunkType::shard(chunk.getShard().toString())));
preCond.append(b.obj());
}
return preCond.arr();
}
/*
* Check that the chunk still exists and return its metadata.
*/
StatusWith<ChunkType> getCurrentChunk(OperationContext* opCtx,
const NamespaceStringOrUUID& nsOrUUID,
const ChunkType& requestedChunk) {
uassert(4683300,
"Config server rejecting commitChunkMigration request that does not have a "
"ChunkVersion",
requestedChunk.isVersionSet() && requestedChunk.getVersion().isSet() &&
requestedChunk.getVersion().epoch().isSet());
BSONObj chunkQuery = BSON(ChunkType::min() << requestedChunk.getMin() << ChunkType::max()
<< requestedChunk.getMax());
if (nsOrUUID.uuid()) {
chunkQuery = chunkQuery.addFields(BSON(ChunkType::collectionUUID << *nsOrUUID.uuid()));
} else {
chunkQuery = chunkQuery.addFields(BSON(ChunkType::ns() << nsOrUUID.nss()->ns()));
}
// Must use local read concern because we're going to perform subsequent writes.
auto findResponseWith =
Grid::get(opCtx)->shardRegistry()->getConfigShard()->exhaustiveFindOnConfig(
opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
ChunkType::ConfigNS,
chunkQuery,
BSONObj(),
1);
if (!findResponseWith.isOK()) {
return findResponseWith.getStatus();
}
if (findResponseWith.getValue().docs.empty()) {
return {ErrorCodes::Error(40165),
str::stream() << "Could not find the chunk (" << requestedChunk.toString()
<< "). Cannot execute the migration commit with invalid chunks."};
}
return uassertStatusOK(ChunkType::fromConfigBSON(findResponseWith.getValue().docs.front()));
}
BSONObj makeCommitChunkTransactionCommand(const NamespaceString& nss,
const ChunkType& migratedChunk,
const boost::optional<ChunkType>& controlChunk,
StringData fromShard,
StringData toShard) {
// Update migratedChunk's version and shard.
BSONArrayBuilder updates;
{
BSONObjBuilder op;
op.append("op", "u");
op.appendBool("b", false); // No upserting
op.append("ns", ChunkType::ConfigNS.ns());
auto chunkID = MONGO_unlikely(migrateCommitInvalidChunkQuery.shouldFail())
? OID::gen()
: migratedChunk.getName();
op.append("o", migratedChunk.toConfigBSON());
BSONObjBuilder q(op.subobjStart("o2"));
q.append(ChunkType::name(), chunkID);
q.done();
updates.append(op.obj());
}
// If we have a controlChunk, update its chunk version.
if (controlChunk) {
BSONObjBuilder op;
op.append("op", "u");
op.appendBool("b", false);
op.append("ns", ChunkType::ConfigNS.ns());
op.append("o", controlChunk->toConfigBSON());
BSONObjBuilder q(op.subobjStart("o2"));
q.append(ChunkType::name(), controlChunk->getName());
q.done();
updates.append(op.obj());
}
// Do not give applyOps a write concern. If applyOps tries to wait for replication, it will
// fail because of the GlobalWrite lock CommitChunkMigration already holds. Replication will
// not be able to take the lock it requires. Include "alwaysUpsert" false since it defaults
// to true and alwaysUpsert overrides the 'b' field.
return BSON("applyOps" << updates.arr() << "alwaysUpsert" << false);
}
/**
* Returns a chunk different from the one being migrated or 'none' if one doesn't exist.
*/
boost::optional<ChunkType> getControlChunkForMigrate(OperationContext* opCtx,
const NamespaceStringOrUUID& nsOrUUID,
const ChunkType& migratedChunk,
const ShardId& fromShard) {
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
BSONObjBuilder queryBuilder;
if (nsOrUUID.uuid()) {
queryBuilder << ChunkType::collectionUUID << *nsOrUUID.uuid();
} else {
queryBuilder << ChunkType::ns(nsOrUUID.nss()->ns());
}
queryBuilder << ChunkType::shard(fromShard.toString());
queryBuilder << ChunkType::min(BSON("$ne" << migratedChunk.getMin()));
auto status =
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
ChunkType::ConfigNS,
queryBuilder.obj(),
{},
1);
auto response = uassertStatusOK(status);
if (response.docs.empty()) {
return boost::none;
}
return uassertStatusOK(ChunkType::fromConfigBSON(response.docs.front()));
}
// Helper function to find collection version and shard version.
StatusWith<ChunkVersion> getMaxChunkVersionFromQueryResponse(
const NamespaceString& nss, const StatusWith<Shard::QueryResponse>& queryResponse) {
if (!queryResponse.isOK()) {
return queryResponse.getStatus();
}
const auto& chunksVector = queryResponse.getValue().docs;
if (chunksVector.empty()) {
return {ErrorCodes::Error(50577),
str::stream() << "Collection '" << nss.ns()
<< "' no longer either exists, is sharded, or has chunks"};
}
return ChunkVersion::parseLegacyWithField(chunksVector.front(), ChunkType::lastmod());
}
// Helper function to get the collection version for nss. Always uses kLocalReadConcern.
StatusWith<ChunkVersion> getCollectionVersion(OperationContext* opCtx, const NamespaceString& nss) {
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto findCollResponse =
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1);
if (!findCollResponse.isOK()) {
return findCollResponse.getStatus();
}
if (findCollResponse.getValue().docs.empty()) {
return {ErrorCodes::Error(5057701),
str::stream() << "Collection '" << nss.ns() << "' no longer either exists"};
}
const CollectionType coll(findCollResponse.getValue().docs[0]);
const auto chunksQuery = [&]() {
if (coll.getTimestamp()) {
return BSON(ChunkType::collectionUUID << coll.getUuid());
} else {
return BSON(ChunkType::ns(coll.getNss().ns()));
}
}();
return getMaxChunkVersionFromQueryResponse(
nss,
Grid::get(opCtx)->shardRegistry()->getConfigShard()->exhaustiveFindOnConfig(
opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
ChunkType::ConfigNS,
chunksQuery, // Query all chunks for this namespace.
BSON(ChunkType::lastmod << -1), // Sort by version.
1)); // Limit 1.
}
// Helper function to get collection version and donor shard version following a merge/move/split
BSONObj getShardAndCollectionVersion(OperationContext* opCtx,
const CollectionType& coll,
const ShardId& fromShard) {
BSONObjBuilder result;
auto swCollectionVersion = getCollectionVersion(opCtx, coll.getNss());
auto collectionVersion = uassertStatusOKWithContext(
std::move(swCollectionVersion), "Couldn't retrieve collection version from config server");
const auto chunksQuery = [&]() {
if (coll.getTimestamp()) {
return BSON(ChunkType::collectionUUID
<< coll.getUuid() << ChunkType::shard()
<< fromShard); // Query all chunks for this namespace and shard.
} else {
return BSON(ChunkType::ns()
<< coll.getNss().ns() << ChunkType::shard()
<< fromShard); // Query all chunks for this namespace and shard.
}
}();
auto swDonorShardVersion = getMaxChunkVersionFromQueryResponse(
coll.getNss(),
Grid::get(opCtx)->shardRegistry()->getConfigShard()->exhaustiveFindOnConfig(
opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
ChunkType::ConfigNS,
chunksQuery,
BSON(ChunkType::lastmod << -1), // Sort by version.
1));
ChunkVersion shardVersion;
if (!swDonorShardVersion.isOK()) {
if (swDonorShardVersion.getStatus().code() == 50577) {
// The query to find 'nss' chunks belonging to the donor shard didn't return any chunks,
// meaning the last chunk for fromShard was donated. Gracefully handle the error.
shardVersion =
ChunkVersion(0, 0, collectionVersion.epoch(), collectionVersion.getTimestamp());
} else {
// Bubble up any other error
uassertStatusOK(swDonorShardVersion);
}
} else {
shardVersion = swDonorShardVersion.getValue();
}
uassert(4914701,
str::stream() << "Aborting due to metadata corruption. Collection version '"
<< collectionVersion.toString() << "' and shard version '"
<< shardVersion.toString() << "'.",
shardVersion.isOlderOrEqualThan(collectionVersion));
collectionVersion.appendWithField(&result, "collectionVersion");
shardVersion.appendWithField(&result, "shardVersion");
return result.obj();
}
void bumpMajorVersionOneChunkPerShard(OperationContext* opCtx,
const NamespaceString& nss,
TxnNumber txnNumber,
const std::vector<ShardId>& shardIds) {
auto curCollectionVersion = uassertStatusOK(getCollectionVersion(opCtx, nss));
ChunkVersion targetChunkVersion(curCollectionVersion.majorVersion() + 1,
0,
curCollectionVersion.epoch(),
curCollectionVersion.getTimestamp());
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto findCollResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1));
uassert(ErrorCodes::ConflictingOperationInProgress,
"Collection does not exist",
!findCollResponse.docs.empty());
const CollectionType coll(findCollResponse.docs[0]);
for (const auto& shardId : shardIds) {
BSONObjBuilder updateBuilder;
BSONObjBuilder updateVersionClause(updateBuilder.subobjStart("$set"));
targetChunkVersion.appendLegacyWithField(&updateVersionClause, ChunkType::lastmod());
updateVersionClause.doneFast();
auto chunkUpdate = updateBuilder.obj();
const auto query = [&]() {
if (coll.getTimestamp()) {
return BSON(ChunkType::collectionUUID << coll.getUuid()
<< ChunkType::shard(shardId.toString()));
} else {
return BSON(ChunkType::ns(coll.getNss().ns())
<< ChunkType::shard(shardId.toString()));
}
}();
auto request = BatchedCommandRequest::buildUpdateOp(ChunkType::ConfigNS,
query, // query
chunkUpdate, // update
false, // upsert
false // multi
);
auto res = ShardingCatalogManager::get(opCtx)->writeToConfigDocumentInTxn(
opCtx, ChunkType::ConfigNS, request, txnNumber);
auto numDocsExpectedModified = 1;
auto numDocsModified = res.getIntField("n");
uassert(5030400,
str::stream() << "Expected to match " << numDocsExpectedModified
<< " docs, but only matched " << numDocsModified
<< " for write request " << request.toString(),
numDocsExpectedModified == numDocsModified);
// There exists a constraint that a chunk version must be unique for a given namespace,
// so the minor version is incremented for each chunk placed.
targetChunkVersion.incMinor();
}
}
NamespaceStringOrUUID getNsOrUUIDForChunkTargeting(const CollectionType& coll) {
if (coll.getTimestamp()) {
return {coll.getNss().db().toString(), coll.getUuid()};
} else {
return {coll.getNss()};
}
}
std::vector<ShardId> getShardsOwningChunksForCollection(OperationContext* opCtx,
const NamespaceString& nss) {
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto findCollResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1));
uassert(
ErrorCodes::Error(5514600), "Collection does not exist", !findCollResponse.docs.empty());
const CollectionType coll(findCollResponse.docs[0]);
const auto nsOrUUID = getNsOrUUIDForChunkTargeting(coll);
DistinctCommandRequest distinctCmd(ChunkType::ConfigNS, ChunkType::shard.name());
if (nsOrUUID.uuid()) {
distinctCmd.setQuery(BSON(ChunkType::collectionUUID << *(nsOrUUID.uuid())));
} else {
distinctCmd.setQuery(BSON(ChunkType::ns(nsOrUUID.nss()->ns())));
}
const auto distinctResult = uassertStatusOK(configShard->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
NamespaceString::kConfigDb.toString(),
distinctCmd.toBSON({}),
Shard::RetryPolicy::kIdempotent));
uassertStatusOK(distinctResult.commandStatus);
const auto valuesElem = distinctResult.response.getField("values");
std::vector<ShardId> shardIds;
for (const auto& shard : valuesElem.Array()) {
shardIds.emplace_back(shard.String());
}
uassert(ErrorCodes::IncompatibleShardingMetadata,
str::stream() << "Tried to find shardIds owning chunks for collection '" << nss.ns()
<< ", but found none",
!shardIds.empty());
return shardIds;
}
} // namespace
StatusWith<BSONObj> ShardingCatalogManager::commitChunkSplit(
OperationContext* opCtx,
const NamespaceString& nss,
const OID& requestEpoch,
const ChunkRange& range,
const std::vector<BSONObj>& splitPoints,
const std::string& shardName) {
// Take _kChunkOpLock in exclusive mode to prevent concurrent chunk splits, merges, and
// migrations
// TODO(SERVER-25359): Replace with a collection-specific lock map to allow splits/merges/
// move chunks on different collections to proceed in parallel
Lock::ExclusiveLock lk(opCtx->lockState(), _kChunkOpLock);
// Get the max chunk version for this namespace.
auto swCollVersion = getCollectionVersion(opCtx, nss);
if (!swCollVersion.isOK()) {
return swCollVersion.getStatus().withContext(
str::stream() << "splitChunk cannot split chunk " << range.toString() << ".");
}
auto collVersion = swCollVersion.getValue();
// Return an error if collection epoch does not match epoch of request.
if (collVersion.epoch() != requestEpoch) {
return {ErrorCodes::StaleEpoch,
str::stream() << "splitChunk cannot split chunk " << range.toString()
<< ". Epoch of collection '" << nss.ns() << "' has changed."
<< " Current epoch: " << collVersion.epoch()
<< ", cmd epoch: " << requestEpoch};
}
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto findCollResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1));
uassert(ErrorCodes::ConflictingOperationInProgress,
"Collection does not exist",
!findCollResponse.docs.empty());
const CollectionType coll(findCollResponse.docs[0]);
// Find the chunk history.
const auto collNsOrUUID = getNsOrUUIDForChunkTargeting(coll);
const auto origChunk = _findChunkOnConfig(opCtx, collNsOrUUID, range.getMin());
if (!origChunk.isOK()) {
repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
return origChunk.getStatus();
}
std::vector<ChunkType> newChunks;
ChunkVersion currentMaxVersion = collVersion;
auto startKey = range.getMin();
auto newChunkBounds(splitPoints);
newChunkBounds.push_back(range.getMax());
auto shouldTakeOriginalChunkID = true;
OID chunkID;
BSONArrayBuilder updates;
for (const auto& endKey : newChunkBounds) {
// Verify the split points are all within the chunk
if (endKey.woCompare(range.getMax()) != 0 && !range.containsKey(endKey)) {
return {ErrorCodes::InvalidOptions,
str::stream() << "Split key " << endKey << " not contained within chunk "
<< range.toString()};
}
// Verify the split points came in increasing order
if (endKey.woCompare(startKey) < 0) {
return {
ErrorCodes::InvalidOptions,
str::stream() << "Split keys must be specified in strictly increasing order. Key "
<< endKey << " was specified after " << startKey << "."};
}
// Verify that splitPoints are not repeated
if (endKey.woCompare(startKey) == 0) {
return {ErrorCodes::InvalidOptions,
str::stream() << "Split on lower bound of chunk [" << startKey.toString()
<< ", " << endKey.toString() << "] is not allowed"};
}
// verify that splits don't use disallowed BSON object format
Status shardKeyStorageStatus =
ShardKeyPattern::checkShardKeyIsValidForMetadataStorage(endKey);
if (!shardKeyStorageStatus.isOK()) {
return shardKeyStorageStatus;
}
// splits only update the 'minor' portion of version
currentMaxVersion.incMinor();
// First chunk takes ID of the original chunk and all other chunks get new IDs. This occurs
// because we perform an update operation below (with upsert true). Keeping the original ID
// ensures we overwrite the old chunk (before the split) without having to perform a delete.
chunkID = shouldTakeOriginalChunkID ? origChunk.getValue().getName() : OID::gen();
shouldTakeOriginalChunkID = false;
// build an update operation against the chunks collection of the config database
// with upsert true
BSONObjBuilder op;
op.append("op", "u");
op.appendBool("b", true);
op.append("ns", ChunkType::ConfigNS.ns());
ChunkType newChunk = origChunk.getValue();
newChunk.setName(chunkID);
newChunk.setVersion(currentMaxVersion);
newChunk.setMin(startKey);
newChunk.setMax(endKey);
op.append("o", newChunk.toConfigBSON());
// add the chunk's _id as the query part of the update statement
BSONObjBuilder q(op.subobjStart("o2"));
q.append(ChunkType::name(), chunkID);
q.done();
updates.append(op.obj());
// remember this chunk info for logging later
newChunks.push_back(std::move(newChunk));
startKey = endKey;
}
BSONArrayBuilder preCond;
{
BSONObjBuilder b;
b.append("ns", ChunkType::ConfigNS.ns());
BSONObj query =
BSON(ChunkType::min() << range.getMin() << ChunkType::max() << range.getMax());
if (origChunk.getValue().getVersion().getTimestamp()) {
query = query.addFields(
BSON(ChunkType::collectionUUID << origChunk.getValue().getCollectionUUID()));
} else {
query = query.addFields(BSON(ChunkType::ns(nss.ns())));
}
b.append("q", BSON("query" << query << "orderby" << BSON(ChunkType::lastmod() << -1)));
{
BSONObjBuilder bb(b.subobjStart("res"));
bb.append(ChunkType::epoch(), requestEpoch);
bb.append(ChunkType::shard(), shardName);
}
preCond.append(b.obj());
}
// apply the batch of updates to local metadata.
const Status applyOpsStatus = Grid::get(opCtx)->catalogClient()->applyChunkOpsDeprecated(
opCtx,
updates.arr(),
preCond.arr(),
nss,
currentMaxVersion,
WriteConcernOptions(),
repl::ReadConcernLevel::kLocalReadConcern);
if (!applyOpsStatus.isOK()) {
return applyOpsStatus;
}
// The current implementation of the split chunk is not idempotent (SERVER-51805).
// Best effort: in order to reduce the probability of having an error, try to execute the
// getShardAndCollectionVersion as soon as the batch of updates is completed
const auto shardAndCollVersion = getShardAndCollectionVersion(opCtx, coll, ShardId(shardName));
// log changes
BSONObjBuilder logDetail;
{
BSONObjBuilder b(logDetail.subobjStart("before"));
b.append(ChunkType::min(), range.getMin());
b.append(ChunkType::max(), range.getMax());
collVersion.appendLegacyWithField(&b, ChunkType::lastmod());
}
if (newChunks.size() == 2) {
appendShortVersion(&logDetail.subobjStart("left"), newChunks[0]);
appendShortVersion(&logDetail.subobjStart("right"), newChunks[1]);
logDetail.append("owningShard", shardName);
ShardingLogging::get(opCtx)->logChange(
opCtx, "split", nss.ns(), logDetail.obj(), WriteConcernOptions());
} else {
BSONObj beforeDetailObj = logDetail.obj();
BSONObj firstDetailObj = beforeDetailObj.getOwned();
const int newChunksSize = newChunks.size();
for (int i = 0; i < newChunksSize; i++) {
BSONObjBuilder chunkDetail;
chunkDetail.appendElements(beforeDetailObj);
chunkDetail.append("number", i + 1);
chunkDetail.append("of", newChunksSize);
appendShortVersion(&chunkDetail.subobjStart("chunk"), newChunks[i]);
chunkDetail.append("owningShard", shardName);
const auto status = ShardingLogging::get(opCtx)->logChangeChecked(
opCtx, "multi-split", nss.ns(), chunkDetail.obj(), WriteConcernOptions());
// Stop logging if the last log op failed because the primary stepped down
if (status.code() == ErrorCodes::InterruptedDueToReplStateChange)
break;
}
}
return shardAndCollVersion;
}
StatusWith<BSONObj> ShardingCatalogManager::commitChunkMerge(
OperationContext* opCtx,
const NamespaceString& nss,
const OID& requestEpoch,
const std::vector<BSONObj>& chunkBoundaries,
const std::string& shardName,
const boost::optional<Timestamp>& validAfter) {
// This method must never be called with empty chunks to merge
invariant(!chunkBoundaries.empty());
// Take _kChunkOpLock in exclusive mode to prevent concurrent chunk splits, merges, and
// migrations
// TODO(SERVER-25359): Replace with a collection-specific lock map to allow splits/merges/
// move chunks on different collections to proceed in parallel
Lock::ExclusiveLock lk(opCtx->lockState(), _kChunkOpLock);
if (!validAfter) {
return {ErrorCodes::IllegalOperation, "chunk operation requires validAfter timestamp"};
}
// Get the max chunk version for this namespace.
auto swCollVersion = getCollectionVersion(opCtx, nss);
if (!swCollVersion.isOK()) {
return swCollVersion.getStatus().withContext(str::stream()
<< "mergeChunk cannot merge chunks.");
}
auto collVersion = swCollVersion.getValue();
// Return an error if epoch of chunk does not match epoch of request
if (collVersion.epoch() != requestEpoch) {
return {ErrorCodes::StaleEpoch,
str::stream() << "Epoch of chunk does not match epoch of request. Chunk epoch: "
<< collVersion.epoch() << ", request epoch: " << requestEpoch};
}
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto findCollResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1));
uassert(ErrorCodes::ConflictingOperationInProgress,
"Collection does not exist",
!findCollResponse.docs.empty());
const CollectionType coll(findCollResponse.docs[0]);
// Check if the chunk(s) have already been merged. If so, return success.
const auto collNsOrUUID = getNsOrUUIDForChunkTargeting(coll);
auto minChunkOnDisk =
uassertStatusOK(_findChunkOnConfig(opCtx, collNsOrUUID, chunkBoundaries.front()));
if (minChunkOnDisk.getMax().woCompare(chunkBoundaries.back()) == 0) {
auto replyWithVersions = getShardAndCollectionVersion(opCtx, coll, ShardId(shardName));
// Makes sure that the last thing we read in getCurrentChunk and
// getShardAndCollectionVersion gets majority written before to return from this command,
// otherwise next RoutingInfo cache refresh from the shard may not see those newest
// information.
repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
return replyWithVersions;
}
// Build chunks to be merged
std::vector<ChunkType> chunksToMerge;
// Do not use the first chunk boundary as a max bound while building chunks
for (size_t i = 1; i < chunkBoundaries.size(); ++i) {
// Read the original chunk from disk to lookup that chunk's '_id' field.
auto currentChunk =
uassertStatusOK(_findChunkOnConfig(opCtx, collNsOrUUID, chunkBoundaries[i - 1]));
// Ensure the chunk boundaries are strictly increasing
if (chunkBoundaries[i].woCompare(currentChunk.getMin()) <= 0) {
return {
ErrorCodes::InvalidOptions,
str::stream()
<< "Chunk boundaries must be specified in strictly increasing order. Boundary "
<< chunkBoundaries[i] << " was specified after " << currentChunk.getMin()
<< "."};
}
chunksToMerge.push_back(std::move(currentChunk));
}
ChunkVersion mergeVersion = collVersion;
mergeVersion.incMinor();
auto updates = buildMergeChunksTransactionUpdates(chunksToMerge, mergeVersion, validAfter);
auto preCond = buildMergeChunksTransactionPrecond(chunksToMerge, collVersion);
// apply the batch of updates to local metadata
const Status applyOpsStatus = Grid::get(opCtx)->catalogClient()->applyChunkOpsDeprecated(
opCtx,
updates,
preCond,
nss,
mergeVersion,
WriteConcernOptions(),
repl::ReadConcernLevel::kLocalReadConcern);
if (!applyOpsStatus.isOK()) {
return applyOpsStatus;
}
// log changes
BSONObjBuilder logDetail;
{
BSONArrayBuilder b(logDetail.subarrayStart("merged"));
for (const auto& chunkToMerge : chunksToMerge) {
b.append(chunkToMerge.toConfigBSON());
}
}
collVersion.appendLegacyWithField(&logDetail, "prevShardVersion");
mergeVersion.appendLegacyWithField(&logDetail, "mergedVersion");
logDetail.append("owningShard", shardName);
ShardingLogging::get(opCtx)->logChange(
opCtx, "merge", nss.ns(), logDetail.obj(), WriteConcernOptions());
return getShardAndCollectionVersion(opCtx, coll, ShardId(shardName));
}
StatusWith<BSONObj> ShardingCatalogManager::commitChunkMigration(
OperationContext* opCtx,
const NamespaceString& nss,
const ChunkType& migratedChunk,
const OID& collectionEpoch,
const ShardId& fromShard,
const ShardId& toShard,
const boost::optional<Timestamp>& validAfter) {
auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
// Must hold the shard lock until the entire commit finishes to serialize with removeShard.
Lock::SharedLock shardLock(opCtx->lockState(), _kShardMembershipLock);
auto shardResult = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting(ReadPreference::PrimaryOnly),
repl::ReadConcernLevel::kLocalReadConcern,
ShardType::ConfigNS,
BSON(ShardType::name(toShard.toString())),
{},
boost::none));
uassert(ErrorCodes::ShardNotFound,
str::stream() << "Shard " << toShard << " does not exist",
!shardResult.docs.empty());
auto shard = uassertStatusOK(ShardType::fromBSON(shardResult.docs.front()));
uassert(ErrorCodes::ShardNotFound,
str::stream() << "Shard " << toShard << " is currently draining",
!shard.getDraining());
// Take _kChunkOpLock in exclusive mode to prevent concurrent chunk splits, merges, and
// migrations.
//
// ConfigSvrCommitChunkMigration commands must be run serially because the new ChunkVersions
// for migrated chunks are generated within the command and must be committed to the database
// before another chunk commit generates new ChunkVersions in the same manner.
//
// TODO(SERVER-25359): Replace with a collection-specific lock map to allow splits/merges/
// move chunks on different collections to proceed in parallel.
// (Note: This is not needed while we have a global lock, taken here only for consistency.)
Lock::ExclusiveLock lk(opCtx->lockState(), _kChunkOpLock);
if (!validAfter) {
return {ErrorCodes::IllegalOperation, "chunk operation requires validAfter timestamp"};
}
auto findCollResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
CollectionType::ConfigNS,
BSON(CollectionType::kNssFieldName << nss.ns()),
{},
1));
uassert(ErrorCodes::ConflictingOperationInProgress,
"Collection does not exist",
!findCollResponse.docs.empty());
const CollectionType coll(findCollResponse.docs[0]);
uassert(ErrorCodes::ConflictingOperationInProgress,
"Collection is undergoing changes and chunks cannot be moved",
coll.getAllowMigrations());
const auto findChunkQuery = [&]() {
if (coll.getTimestamp()) {
return BSON(ChunkType::collectionUUID() << coll.getUuid());
} else {
return BSON(ChunkType::ns() << coll.getNss().ns());
}
}();
auto findResponse = uassertStatusOK(
configShard->exhaustiveFindOnConfig(opCtx,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
ChunkType::ConfigNS,
findChunkQuery,
BSON(ChunkType::lastmod << -1),
1));
uassert(ErrorCodes::IncompatibleShardingMetadata,
str::stream() << "Tried to find max chunk version for collection '" << nss.ns()
<< ", but found no chunks",
!findResponse.docs.empty());
const auto chunk = uassertStatusOK(ChunkType::fromConfigBSON(findResponse.docs[0]));
const auto currentCollectionVersion = chunk.getVersion();
if (MONGO_unlikely(migrationCommitVersionError.shouldFail())) {
uasserted(ErrorCodes::StaleEpoch,
"Failpoint 'migrationCommitVersionError' generated error");
}
// It is possible for a migration to end up running partly without the protection of the
// distributed lock if the config primary stepped down since the start of the migration and
// failed to recover the migration. Check that the collection has not been dropped and recreated
// or had its shard key refined since the migration began, unbeknown to the shard when the
// command was sent.
if (currentCollectionVersion.epoch() != collectionEpoch) {
return {ErrorCodes::StaleEpoch,
str::stream() << "The epoch of collection '" << nss.ns()
<< "' has changed since the migration began. The config server's "
"collection version epoch is now '"
<< currentCollectionVersion.epoch().toString()
<< "', but the shard's is " << collectionEpoch.toString()
<< "'. Aborting migration commit for chunk ("
<< migratedChunk.getRange().toString() << ")."};
}
// Check if chunk still exists and which shard owns it
const auto collNsOrUUID = getNsOrUUIDForChunkTargeting(coll);
auto swCurrentChunk = getCurrentChunk(opCtx, collNsOrUUID, migratedChunk);
if (!swCurrentChunk.isOK()) {
return swCurrentChunk.getStatus();
}
auto currentChunk = swCurrentChunk.getValue();
if (currentChunk.getShard() == toShard) {
// The commit was already done successfully
auto replyWithVersions = getShardAndCollectionVersion(opCtx, coll, fromShard);
// Makes sure that the last thing we read in getCurrentChunk and
// getShardAndCollectionVersion gets majority written before to return from this command,
// otherwise next RoutingInfo cache refresh from the shard may not see those newest
// information.
repl::ReplClientInfo::forClient(opCtx->getClient()).setLastOpToSystemLastOpTime(opCtx);
return replyWithVersions;
}
uassert(4914702,
str::stream() << "Migrated chunk " << migratedChunk.toString()
<< " from ns: " << nss.ns() << " not owned by donor " << fromShard
<< " neither by recipient " << toShard,
currentChunk.getShard() == fromShard);