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citus/src/backend/distributed/shared_library_init.c

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/*-------------------------------------------------------------------------
*
* shared_library_init.c
* Functionality related to the initialization of the Citus extension.
*
* Copyright (c) Citus Data, Inc.
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <limits.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "fmgr.h"
#include "miscadmin.h"
#include "citus_version.h"
#include "commands/explain.h"
#include "executor/executor.h"
#include "distributed/backend_data.h"
#include "distributed/citus_nodefuncs.h"
#include "distributed/commands.h"
#include "distributed/commands/multi_copy.h"
#include "distributed/commands/utility_hook.h"
#include "distributed/connection_management.h"
#include "distributed/distributed_deadlock_detection.h"
#include "distributed/local_executor.h"
#include "distributed/maintenanced.h"
#include "distributed/master_metadata_utility.h"
#include "distributed/master_protocol.h"
#include "distributed/metadata_cache.h"
#include "distributed/metadata_sync.h"
#include "distributed/multi_explain.h"
#include "distributed/multi_join_order.h"
#include "distributed/multi_logical_optimizer.h"
#include "distributed/distributed_planner.h"
#include "distributed/multi_router_executor.h"
#include "distributed/multi_router_planner.h"
#include "distributed/multi_server_executor.h"
#include "distributed/pg_dist_partition.h"
#include "distributed/placement_connection.h"
#include "distributed/relation_access_tracking.h"
#include "distributed/run_from_same_connection.h"
#include "distributed/query_pushdown_planning.h"
#include "distributed/query_stats.h"
#include "distributed/remote_commands.h"
#include "distributed/shared_library_init.h"
#include "distributed/statistics_collection.h"
#include "distributed/subplan_execution.h"
#include "distributed/task_tracker.h"
#include "distributed/transaction_management.h"
#include "distributed/transaction_recovery.h"
#include "distributed/worker_manager.h"
#include "distributed/worker_protocol.h"
#include "distributed/worker_shard_visibility.h"
#include "port/atomics.h"
#include "postmaster/postmaster.h"
#include "optimizer/planner.h"
#include "optimizer/paths.h"
#include "tcop/tcopprot.h"
#include "utils/guc.h"
#include "utils/guc_tables.h"
#include "utils/varlena.h"
/* marks shared object as one loadable by the postgres version compiled against */
PG_MODULE_MAGIC;
static char *CitusVersion = CITUS_VERSION;
void _PG_init(void);
static void ResizeStackToMaximumDepth(void);
static void multi_log_hook(ErrorData *edata);
static void CreateRequiredDirectories(void);
static void RegisterCitusConfigVariables(void);
static bool ErrorIfNotASuitableDeadlockFactor(double *newval, void **extra,
GucSource source);
static void NormalizeWorkerListPath(void);
static bool NodeConninfoGucCheckHook(char **newval, void **extra, GucSource source);
static void NodeConninfoGucAssignHook(const char *newval, void *extra);
static bool StatisticsCollectionGucCheckHook(bool *newval, void **extra, GucSource
source);
/* static variable to hold value of deprecated GUC variable */
static bool ExpireCachedShards = false;
static int LargeTableShardCount = 0;
static int CitusSSLMode = 0;
/* *INDENT-OFF* */
/* GUC enum definitions */
static const struct config_enum_entry propagate_set_commands_options[] = {
{"none", PROPSETCMD_NONE, false},
{"local", PROPSETCMD_LOCAL, false},
{NULL, 0, false}
};
static const struct config_enum_entry task_assignment_policy_options[] = {
{ "greedy", TASK_ASSIGNMENT_GREEDY, false },
{ "first-replica", TASK_ASSIGNMENT_FIRST_REPLICA, false },
{ "round-robin", TASK_ASSIGNMENT_ROUND_ROBIN, false },
{ NULL, 0, false }
};
static const struct config_enum_entry replication_model_options[] = {
{ "statement", REPLICATION_MODEL_COORDINATOR, false },
{ "streaming", REPLICATION_MODEL_STREAMING, false },
{ NULL, 0, false }
};
static const struct config_enum_entry task_executor_type_options[] = {
{ "adaptive", MULTI_EXECUTOR_ADAPTIVE, false },
{ "real-time", MULTI_EXECUTOR_REAL_TIME, false },
{ "task-tracker", MULTI_EXECUTOR_TASK_TRACKER, false },
{ NULL, 0, false }
};
static const struct config_enum_entry shard_placement_policy_options[] = {
{ "local-node-first", SHARD_PLACEMENT_LOCAL_NODE_FIRST, false },
{ "round-robin", SHARD_PLACEMENT_ROUND_ROBIN, false },
{ "random", SHARD_PLACEMENT_RANDOM, false },
{ NULL, 0, false }
};
static const struct config_enum_entry use_secondary_nodes_options[] = {
{ "never", USE_SECONDARY_NODES_NEVER, false },
{ "always", USE_SECONDARY_NODES_ALWAYS, false },
{ NULL, 0, false }
};
static const struct config_enum_entry shard_commit_protocol_options[] = {
{ "1pc", COMMIT_PROTOCOL_1PC, false },
{ "2pc", COMMIT_PROTOCOL_2PC, false },
{ NULL, 0, false }
};
static const struct config_enum_entry multi_task_query_log_level_options[] = {
{ "off", MULTI_TASK_QUERY_INFO_OFF, false },
{ "debug", DEBUG2, false },
{ "log", LOG, false },
{ "notice", NOTICE, false },
{ "warning", WARNING, false },
{ "error", ERROR, false },
{ NULL, 0, false }
};
static const struct config_enum_entry multi_shard_modify_connection_options[] = {
{ "parallel", PARALLEL_CONNECTION, false },
{ "sequential", SEQUENTIAL_CONNECTION, false },
{ NULL, 0, false }
};
/* *INDENT-ON* */
/* shared library initialization function */
void
_PG_init(void)
{
if (!process_shared_preload_libraries_in_progress)
{
ereport(ERROR, (errmsg("Citus can only be loaded via shared_preload_libraries"),
errhint("Add citus to shared_preload_libraries configuration "
"variable in postgresql.conf in master and workers. Note "
"that citus should be at the beginning of "
"shared_preload_libraries.")));
}
/*
* Perform checks before registering any hooks, to avoid erroring out in a
* partial state.
*
* In many cases (e.g. planner and utility hook, to run inside
* pg_stat_statements et. al.) we have to be loaded before other hooks
* (thus as the innermost/last running hook) to be able to do our
* duties. For simplicity insist that all hooks are previously unused.
*/
if (planner_hook != NULL || ProcessUtility_hook != NULL ||
ExecutorStart_hook != NULL || ExecutorRun_hook != NULL)
{
ereport(ERROR, (errmsg("Citus has to be loaded first"),
errhint("Place citus at the beginning of "
"shared_preload_libraries.")));
}
ResizeStackToMaximumDepth();
/*
* Extend the database directory structure before continuing with
* initialization - one of the later steps might require them to exist.
* If in a sub-process (windows / EXEC_BACKEND) this already has been
* done.
*/
if (!IsUnderPostmaster)
{
CreateRequiredDirectories();
}
InitConnParams();
/*
* Register Citus configuration variables. Do so before intercepting
* hooks or calling initialization functions, in case we want to do the
* latter in a configuration dependent manner.
*/
RegisterCitusConfigVariables();
/* make our additional node types known */
RegisterNodes();
/* make our custom scan nodes known */
RegisterCitusCustomScanMethods();
/* intercept planner */
planner_hook = distributed_planner;
/* register utility hook */
ProcessUtility_hook = multi_ProcessUtility;
/* register for planner hook */
set_rel_pathlist_hook = multi_relation_restriction_hook;
set_join_pathlist_hook = multi_join_restriction_hook;
ExecutorStart_hook = CitusExecutorStart;
ExecutorRun_hook = CitusExecutorRun;
/* register hook for error messages */
emit_log_hook = multi_log_hook;
InitializeMaintenanceDaemon();
/* organize that task tracker is started once server is up */
TaskTrackerRegister();
/* initialize coordinated transaction management */
InitializeTransactionManagement();
InitializeBackendManagement();
InitializeConnectionManagement();
InitPlacementConnectionManagement();
InitializeCitusQueryStats();
/* enable modification of pg_catalog tables during pg_upgrade */
if (IsBinaryUpgrade)
{
SetConfigOption("allow_system_table_mods", "true", PGC_POSTMASTER,
PGC_S_OVERRIDE);
}
}
/*
* Stack size increase during high memory load may cause unexpected crashes.
* With this alloca call, we are increasing stack size explicitly, so that if
* it is not possible to increase stack size, we will get an OOM error instead
* of a crash.
*
* This function is called on backend startup. The allocated memory will
* automatically be released at the end of the function's scope. However, we'd
* have already expanded the stack and it wouldn't shrink back. So, in a sense,
* per backend we're securing max_stack_depth kB's of memory on the stack upfront.
*
* Not all the backends require max_stack_depth kB's on the stack, so we might end
* up with unnecessary allocations. However, the default value is 2MB, which seems
* an acceptable trade-off. Also, allocating memory upfront may perform better
* under some circumstances.
*/
static void
ResizeStackToMaximumDepth(void)
{
#ifndef WIN32
volatile char *stack_resizer = NULL;
long max_stack_depth_bytes = max_stack_depth * 1024L;
stack_resizer = alloca(max_stack_depth_bytes);
/*
* Different architectures might have different directions while
* growing the stack. So, touch both ends.
*/
stack_resizer[0] = 0;
stack_resizer[max_stack_depth_bytes - 1] = 0;
/*
* Passing the address to external function also prevents the function
* from being optimized away, and the debug elog can also help with
* diagnosis if needed.
*/
elog(DEBUG5, "entry stack is at %p, increased to %p, the top and bottom values of "
"the stack is %d and %d", &stack_resizer[0],
&stack_resizer[max_stack_depth_bytes - 1],
stack_resizer[max_stack_depth_bytes - 1], stack_resizer[0]);
#endif
}
/*
* multi_log_hook intercepts postgres log commands. We use this to override
* postgres error messages when they're not specific enough for the users.
*/
static void
multi_log_hook(ErrorData *edata)
{
/*
* Show the user a meaningful error message when a backend is cancelled
* by the distributed deadlock detection.
*/
if (edata->elevel == ERROR && edata->sqlerrcode == ERRCODE_QUERY_CANCELED &&
MyBackendGotCancelledDueToDeadlock())
{
edata->sqlerrcode = ERRCODE_T_R_DEADLOCK_DETECTED;
edata->message = "canceling the transaction since it was "
"involved in a distributed deadlock";
}
}
/*
* StartupCitusBackend initializes per-backend infrastructure, and is called
* the first time citus is used in a database.
*
* NB: All code here has to be able to cope with this routine being called
* multiple times in the same backend. This will e.g. happen when the
* extension is created or upgraded.
*/
void
StartupCitusBackend(void)
{
InitializeMaintenanceDaemonBackend();
InitializeBackendData();
}
/*
* CreateRequiredDirectories - Create directories required for Citus to
* function.
*
* These used to be created by initdb, but that's not possible anymore.
*/
static void
CreateRequiredDirectories(void)
{
int dirNo = 0;
const char *subdirs[] = {
"pg_foreign_file",
"pg_foreign_file/cached",
"base/" PG_JOB_CACHE_DIR
};
for (dirNo = 0; dirNo < lengthof(subdirs); dirNo++)
{
int ret = mkdir(subdirs[dirNo], S_IRWXU);
if (ret != 0 && errno != EEXIST)
{
ereport(ERROR, (errcode_for_file_access(),
errmsg("could not create directory \"%s\": %m",
subdirs[dirNo])));
}
}
}
/* Register Citus configuration variables. */
static void
RegisterCitusConfigVariables(void)
{
DefineCustomIntVariable(
"citus.node_connection_timeout",
gettext_noop("Sets the maximum duration to connect to worker nodes."),
NULL,
&NodeConnectionTimeout,
5000, 10, 60 * 60 * 1000,
PGC_USERSET,
GUC_UNIT_MS,
NULL, NULL, NULL);
/* keeping temporarily for updates from pre-6.0 versions */
DefineCustomStringVariable(
"citus.worker_list_file",
gettext_noop("Sets the server's \"worker_list\" configuration file."),
NULL,
&WorkerListFileName,
NULL,
PGC_POSTMASTER,
GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
NormalizeWorkerListPath();
DefineCustomIntVariable(
"citus.sslmode",
gettext_noop("This variable has been deprecated. Use the citus.node_conninfo "
"GUC instead."),
NULL,
&CitusSSLMode,
0, 0, 32,
PGC_POSTMASTER,
GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.binary_master_copy_format",
gettext_noop("Use the binary master copy format."),
gettext_noop("When enabled, data is copied from workers to the master "
"in PostgreSQL's binary serialization format."),
&BinaryMasterCopyFormat,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.binary_worker_copy_format",
gettext_noop("Use the binary worker copy format."),
gettext_noop("When enabled, data is copied from workers to workers "
"in PostgreSQL's binary serialization format when "
"joining large tables."),
&BinaryWorkerCopyFormat,
false,
PGC_SIGHUP,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.expire_cached_shards",
gettext_noop("This GUC variable has been deprecated."),
NULL,
&ExpireCachedShards,
false,
PGC_SIGHUP,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_local_execution",
gettext_noop("Enables queries on shards that are local to the current node "
"to be planned and executed locally."),
NULL,
&EnableLocalExecution,
true,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_single_hash_repartition_joins",
gettext_noop("Enables single hash repartitioning between hash "
"distributed tables"),
NULL,
&EnableSingleHashRepartitioning,
false,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_fast_path_router_planner",
gettext_noop("Enables fast path router planner"),
NULL,
&EnableFastPathRouterPlanner,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.override_table_visibility",
gettext_noop("Enables replacing occurencens of pg_catalog.pg_table_visible() "
"with pg_catalog.citus_table_visible()"),
gettext_noop("When enabled, shards on the Citus MX worker (data) nodes would be "
"filtered out by many psql commands to provide better user "
"experience."),
&OverrideTableVisibility,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enforce_foreign_key_restrictions",
gettext_noop("Enforce restrictions while querying distributed/reference "
"tables with foreign keys"),
gettext_noop("When enabled, cascading modifications from reference tables "
"to distributed tables are traced and acted accordingly "
"to avoid creating distributed deadlocks and ensure correctness."),
&EnforceForeignKeyRestrictions,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.subquery_pushdown",
gettext_noop("Enables supported subquery pushdown to workers."),
NULL,
&SubqueryPushdown,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.log_multi_join_order",
gettext_noop("Logs the distributed join order to the server log."),
gettext_noop("We use this private configuration entry as a debugging aid. "
"If enabled, we print the distributed join order."),
&LogMultiJoinOrder,
false,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.log_remote_commands",
gettext_noop("Log queries sent to other nodes in the server log"),
NULL,
&LogRemoteCommands,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.log_local_commands",
gettext_noop("Log queries that are executed locally, can be overriden by "
"citus.log_remote_commands"),
NULL,
&LogLocalCommands,
false,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.log_distributed_deadlock_detection",
gettext_noop("Log distributed deadlock detection related processing in "
"the server log"),
NULL,
&LogDistributedDeadlockDetection,
false,
PGC_SIGHUP,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.explain_distributed_queries",
gettext_noop("Enables Explain for distributed queries."),
gettext_noop("When enabled, the Explain command shows remote and local "
"plans when used with a distributed query. It is enabled "
"by default, but can be disabled for regression tests."),
&ExplainDistributedQueries,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.explain_all_tasks",
gettext_noop("Enables showing output for all tasks in Explain."),
gettext_noop("The Explain command for distributed queries shows "
"the remote plan for a single task by default. When "
"this configuration entry is enabled, the plan for "
"all tasks is shown, but the Explain takes longer."),
&ExplainAllTasks,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.all_modifications_commutative",
gettext_noop("Bypasses commutativity checks when enabled"),
NULL,
&AllModificationsCommutative,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomRealVariable(
"citus.distributed_deadlock_detection_factor",
gettext_noop("Sets the time to wait before checking for distributed "
"deadlocks. Postgres' deadlock_timeout setting is "
"multiplied with the value. If the value is set to"
"1000, distributed deadlock detection is disabled."),
NULL,
&DistributedDeadlockDetectionTimeoutFactor,
2.0, -1.0, 1000.0,
PGC_SIGHUP,
0,
ErrorIfNotASuitableDeadlockFactor, NULL, NULL);
DefineCustomIntVariable(
"citus.recover_2pc_interval",
gettext_noop("Sets the time to wait between recovering 2PCs."),
gettext_noop("2PC transaction recovery needs to run every so often "
"to clean up records in pg_dist_transaction and "
"potentially roll failed 2PCs forward. This setting "
"determines how often recovery should run, "
"use -1 to disable."),
&Recover2PCInterval,
60000, -1, 7 * 24 * 3600 * 1000,
PGC_SIGHUP,
GUC_UNIT_MS,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.metadata_sync_interval",
gettext_noop("Sets the time to wait between metadata syncs."),
gettext_noop("metadata sync needs to run every so often "
"to synchronize metadata to metadata nodes "
"that are out of sync."),
&MetadataSyncInterval,
60000, 1, 7 * 24 * 3600 * 1000,
PGC_SIGHUP,
GUC_UNIT_MS | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.metadata_sync_retry_interval",
gettext_noop("Sets the interval to retry failed metadata syncs."),
gettext_noop("metadata sync needs to run every so often "
"to synchronize metadata to metadata nodes "
"that are out of sync."),
&MetadataSyncRetryInterval,
5000, 1, 7 * 24 * 3600 * 1000,
PGC_SIGHUP,
GUC_UNIT_MS | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.select_opens_transaction_block",
gettext_noop("Open transaction blocks for SELECT commands"),
gettext_noop("When enabled, Citus will always send a BEGIN to workers when "
"running a distributed SELECT in a transaction block (the "
"default). When disabled, Citus will only send BEGIN before "
"the first write or other operation that requires a distributed "
"transaction, meaning the SELECT on the worker commits "
"immediately, releasing any locks and apply any changes made "
"through function calls even if the distributed transaction "
"aborts."),
&SelectOpensTransactionBlock,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.function_opens_transaction_block",
gettext_noop("Open transaction blocks for function calls"),
gettext_noop("When enabled, Citus will always send a BEGIN to workers when "
"running distributed queres in a function. When disabled, the "
"queries may be committed immediately after the statemnent "
"completes. Disabling this flag is dangerous, it is only provided "
"for backwards compatibility with pre-8.2 behaviour."),
&FunctionOpensTransactionBlock,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.force_max_query_parallelization",
gettext_noop("Open as many connections as possible to maximize query "
"parallelization"),
gettext_noop("When enabled, Citus will force the executor to use "
"as many connections as possible while executing a "
"parallel distributed query. If not enabled, the executor"
"might choose to use less connections to optimize overall "
"query execution throughput. Internally, setting this true "
"will end up with using one connection per task."),
&ForceMaxQueryParallelization,
false,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.executor_slow_start_interval",
gettext_noop("Time to wait between opening connections to the same worker node"),
gettext_noop("When the individual tasks of a multi-shard query take very "
"little time, they can often be finished over a single (often "
"already cached) connection. To avoid redundantly opening "
"additional connections, the executor waits between connection "
"attempts for the configured number of milliseconds. At the end "
"of the interval, it increases the number of connections it is "
"allowed to open next time."),
&ExecutorSlowStartInterval,
10, 0, INT_MAX,
PGC_USERSET,
GUC_UNIT_MS | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_deadlock_prevention",
gettext_noop("Avoids deadlocks by preventing concurrent multi-shard commands"),
gettext_noop("Multi-shard modifications such as UPDATE, DELETE, and "
"INSERT...SELECT are typically executed in parallel. If multiple "
"such commands run concurrently and affect the same rows, then "
"they are likely to deadlock. When enabled, this flag prevents "
"multi-shard modifications from running concurrently when they "
"affect the same shards in order to prevent deadlocks."),
&EnableDeadlockPrevention,
true,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_ddl_propagation",
gettext_noop("Enables propagating DDL statements to worker shards"),
NULL,
&EnableDDLPropagation,
true,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_object_propagation",
gettext_noop("Enables propagating object creation for more complex objects, "
"schema's will always be created"),
NULL,
&EnableDependencyCreation,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_create_type_propagation",
gettext_noop("Enables propagating of CREATE TYPE statements to workers"),
NULL,
&EnableCreateTypePropagation,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.propagate_set_commands",
gettext_noop("Sets which SET commands are propagated to workers."),
NULL,
&PropagateSetCommands,
PROPSETCMD_NONE,
propagate_set_commands_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_router_execution",
gettext_noop("Enables router execution"),
NULL,
&EnableRouterExecution,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.shard_count",
gettext_noop("Sets the number of shards for a new hash-partitioned table"
"created with create_distributed_table()."),
NULL,
&ShardCount,
32, 1, 64000,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.shard_replication_factor",
gettext_noop("Sets the replication factor for shards."),
gettext_noop("Shards are replicated across nodes according to this "
"replication factor. Note that shards read this "
"configuration value at sharded table creation time, "
"and later reuse the initially read value."),
&ShardReplicationFactor,
1, 1, 100,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.shard_max_size",
gettext_noop("Sets the maximum size a shard will grow before it gets split."),
gettext_noop("Shards store table and file data. When the source "
"file's size for one shard exceeds this configuration "
"value, the database ensures that either a new shard "
"gets created, or the current one gets split. Note that "
"shards read this configuration value at sharded table "
"creation time, and later reuse the initially read value."),
&ShardMaxSize,
1048576, 256, INT_MAX, /* max allowed size not set to MAX_KILOBYTES on purpose */
PGC_USERSET,
GUC_UNIT_KB,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.sort_returning",
gettext_noop("Sorts the RETURNING clause to get consistent test output"),
gettext_noop("This feature is not intended for users. It is developed "
"to get consistent regression test outputs. When enabled, "
"the RETURNING clause returns the tuples sorted. The sort "
"is done for all the entries, starting from the first one."
"Finally, the sorting is done in ASC order."),
&SortReturning,
false,
PGC_SUSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_intermediate_result_size",
gettext_noop("Sets the maximum size of the intermediate results in KB for "
"CTEs and complex subqueries."),
NULL,
&MaxIntermediateResult,
1048576, -1, MAX_KILOBYTES,
PGC_USERSET,
GUC_UNIT_KB,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_adaptive_executor_pool_size",
gettext_noop("Sets the maximum number of connections per worker node used by "
"the adaptive executor to execute a multi-shard command"),
gettext_noop("The adaptive executor may open multiple connections per worker "
"node when running multi-shard commands to parallelize the command "
"across multiple cores on the worker. This setting specifies the "
"maximum number of connections it will open. The number of "
"connections is also bounded by the number of shards on the node. "
"This setting can be used to reduce the memory usage of a query "
"and allow a higher degree of concurrency when concurrent "
"multi-shard queries open too many connections to a worker."),
&MaxAdaptiveExecutorPoolSize,
16, 1, INT_MAX,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_worker_nodes_tracked",
gettext_noop("Sets the maximum number of worker nodes that are tracked."),
gettext_noop("Worker nodes' network locations, their membership and "
"health status are tracked in a shared hash table on "
"the master node. This configuration value limits the "
"size of the hash table, and consequently the maximum "
"number of worker nodes that can be tracked."),
&MaxWorkerNodesTracked,
2048, 8, INT_MAX,
PGC_POSTMASTER,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.remote_task_check_interval",
gettext_noop("Sets the frequency at which we check job statuses."),
gettext_noop("The master node assigns tasks to workers nodes, and "
"then regularly checks with them about each task's "
"progress. This configuration value sets the time "
"interval between two consequent checks."),
&RemoteTaskCheckInterval,
10, 1, INT_MAX,
PGC_USERSET,
GUC_UNIT_MS,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.task_tracker_delay",
gettext_noop("Task tracker sleep time between task management rounds."),
gettext_noop("The task tracker process wakes up regularly, walks over "
"all tasks assigned to it, and schedules and executes these "
"tasks. Then, the task tracker sleeps for a time period "
"before walking over these tasks again. This configuration "
"value determines the length of that sleeping period."),
&TaskTrackerDelay,
200, 1, 100000,
PGC_SIGHUP,
GUC_UNIT_MS,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_cached_conns_per_worker",
gettext_noop("Sets the maximum number of connections to cache per worker."),
gettext_noop("Each backend opens connections to the workers to query the "
"shards. At the end of the transaction, the configurated number "
"of connections is kept open to speed up subsequent commands. "
"Increasing this value will reduce the latency of multi-shard "
"queries, but increases overhead on the workers"),
&MaxCachedConnectionsPerWorker,
1, 0, INT_MAX,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_assign_task_batch_size",
gettext_noop("Sets the maximum number of tasks to assign per round."),
gettext_noop("The master node synchronously assigns tasks to workers in "
"batches. Bigger batches allow for faster task assignment, "
"but it may take longer for all workers to get tasks "
"if the number of workers is large. This configuration "
"value controls the maximum batch size."),
&MaxAssignTaskBatchSize,
64, 1, INT_MAX,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_tracked_tasks_per_node",
gettext_noop("Sets the maximum number of tracked tasks per node."),
gettext_noop("The task tracker processes keeps all assigned tasks in "
"a shared hash table, and schedules and executes these "
"tasks as appropriate. This configuration value limits "
"the size of the hash table, and therefore the maximum "
"number of tasks that can be tracked at any given time."),
&MaxTrackedTasksPerNode,
1024, 8, INT_MAX,
PGC_POSTMASTER,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_running_tasks_per_node",
gettext_noop("Sets the maximum number of tasks to run concurrently per node."),
gettext_noop("The task tracker process schedules and executes the tasks "
"assigned to it as appropriate. This configuration value "
"sets the maximum number of tasks to execute concurrently "
"on one node at any given time."),
&MaxRunningTasksPerNode,
8, 1, INT_MAX,
PGC_SIGHUP,
0,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.partition_buffer_size",
gettext_noop("Sets the buffer size to use for partition operations."),
gettext_noop("Worker nodes allow for table data to be repartitioned "
"into multiple text files, much like Hadoop's Map "
"command. This configuration value sets the buffer size "
"to use per partition operation. After the buffer fills "
"up, we flush the repartitioned data into text files."),
&PartitionBufferSize,
8192, 0, (INT_MAX / 1024), /* result stored in int variable */
PGC_USERSET,
GUC_UNIT_KB,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.large_table_shard_count",
gettext_noop("This variable has been deprecated."),
gettext_noop("Consider reference tables instead"),
&LargeTableShardCount,
4, 1, 10000,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.limit_clause_row_fetch_count",
gettext_noop("Number of rows to fetch per task for limit clause optimization."),
gettext_noop("Select queries get partitioned and executed as smaller "
"tasks. In some cases, select queries with limit clauses "
"may need to fetch all rows from each task to generate "
"results. In those cases, and where an approximation would "
"produce meaningful results, this configuration value sets "
"the number of rows to fetch from each task."),
&LimitClauseRowFetchCount,
-1, -1, INT_MAX,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomRealVariable(
"citus.count_distinct_error_rate",
gettext_noop("Desired error rate when calculating count(distinct) "
"approximates using the postgresql-hll extension. "
"0.0 disables approximations for count(distinct); 1.0 "
"provides no guarantees about the accuracy of results."),
NULL,
&CountDistinctErrorRate,
0.0, 0.0, 1.0,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.multi_shard_commit_protocol",
gettext_noop("Sets the commit protocol for commands modifying multiple shards."),
gettext_noop("When a failure occurs during commands that modify multiple "
"shards, two-phase commit is required to ensure data is never lost "
"and this is the default. However, changing to 1pc may give small "
"performance benefits."),
&MultiShardCommitProtocol,
COMMIT_PROTOCOL_2PC,
shard_commit_protocol_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.single_shard_commit_protocol",
gettext_noop(
"Sets the commit protocol for commands modifying a single shards with multiple replicas."),
gettext_noop("When a failure occurs during commands that modify multiple "
"replicas, two-phase commit is required to ensure data is never lost "
"and this is the default. However, changing to 1pc may give small "
"performance benefits."),
&SingleShardCommitProtocol,
COMMIT_PROTOCOL_2PC,
shard_commit_protocol_options,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.task_assignment_policy",
gettext_noop("Sets the policy to use when assigning tasks to worker nodes."),
gettext_noop("The master node assigns tasks to worker nodes based on shard "
"locations. This configuration value specifies the policy to "
"use when making these assignments. The greedy policy aims to "
"evenly distribute tasks across worker nodes, first-replica just "
"assigns tasks in the order shard placements were created, "
"and the round-robin policy assigns tasks to worker nodes in "
"a round-robin fashion."),
&TaskAssignmentPolicy,
TASK_ASSIGNMENT_GREEDY,
task_assignment_policy_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.replication_model",
gettext_noop("Sets the replication model to be used for distributed tables."),
gettext_noop("Depending upon the execution environment, statement- or streaming-"
"based replication modes may be employed. Though most Citus deploy-"
"ments will simply use statement replication, hosted and MX-style"
"deployments should set this parameter to 'streaming'."),
&ReplicationModel,
REPLICATION_MODEL_COORDINATOR,
replication_model_options,
PGC_SUSET,
GUC_SUPERUSER_ONLY,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.task_executor_type",
gettext_noop("Sets the executor type to be used for distributed queries."),
gettext_noop("The master node chooses between two different executor types "
"when executing a distributed query.The real-time executor is "
"optimal for simple key-value lookup queries and queries that "
"involve aggregations and/or co-located joins on multiple shards. "
"The task-tracker executor is optimal for long-running, complex "
"queries that touch thousands of shards and/or that involve table "
"repartitioning."),
&TaskExecutorType,
MULTI_EXECUTOR_ADAPTIVE,
task_executor_type_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_repartition_joins",
gettext_noop("Allows Citus to use task-tracker executor when necessary."),
NULL,
&EnableRepartitionJoins,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.shard_placement_policy",
gettext_noop("Sets the policy to use when choosing nodes for shard placement."),
gettext_noop("The master node chooses which worker nodes to place new shards "
"on. This configuration value specifies the policy to use when "
"selecting these nodes. The local-node-first policy places the "
"first replica on the client node and chooses others randomly. "
"The round-robin policy aims to distribute shards evenly across "
"the cluster by selecting nodes in a round-robin fashion."
"The random policy picks all workers randomly."),
&ShardPlacementPolicy,
SHARD_PLACEMENT_ROUND_ROBIN, shard_placement_policy_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.use_secondary_nodes",
gettext_noop("Sets the policy to use when choosing nodes for SELECT queries."),
NULL,
&ReadFromSecondaries,
USE_SECONDARY_NODES_NEVER, use_secondary_nodes_options,
PGC_SU_BACKEND,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.multi_task_query_log_level",
gettext_noop("Sets the level of multi task query execution log messages"),
NULL,
&MultiTaskQueryLogLevel,
MULTI_TASK_QUERY_INFO_OFF, multi_task_query_log_level_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomEnumVariable(
"citus.multi_shard_modify_mode",
gettext_noop("Sets the connection type for multi shard modify queries"),
NULL,
&MultiShardConnectionType,
PARALLEL_CONNECTION, multi_shard_modify_connection_options,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomStringVariable(
"citus.version",
gettext_noop("Shows the Citus library version"),
NULL,
&CitusVersion,
CITUS_VERSION,
PGC_INTERNAL,
0,
NULL, NULL, NULL);
DefineCustomStringVariable(
"citus.cluster_name",
gettext_noop("Which cluster this node is a part of"),
NULL,
&CurrentCluster,
"default",
PGC_SU_BACKEND,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.writable_standby_coordinator",
gettext_noop("Enables simple DML via a streaming replica of the coordinator"),
NULL,
&WritableStandbyCoordinator,
false,
PGC_USERSET,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_version_checks",
gettext_noop("Enables version checks during CREATE/ALTER EXTENSION commands"),
NULL,
&EnableVersionChecks,
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_unique_job_ids",
gettext_noop("Enables unique job IDs by prepending the local process ID and "
"group ID. This should usually be enabled, but can be disabled "
"for repeatable output in regression tests."),
NULL,
&EnableUniqueJobIds,
true,
PGC_USERSET,
GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.next_shard_id",
gettext_noop("Set the next shard ID to use in shard creation."),
gettext_noop("Shard IDs are normally generated using a sequence. If "
"next_shard_id is set to a non-zero value, shard IDs will "
"instead be generated by incrementing from the value of "
"this GUC and this will be reflected in the GUC. This is "
"mainly useful to ensure consistent shard IDs when running "
"tests in parallel."),
&NextShardId,
0, 0, INT_MAX,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.next_placement_id",
gettext_noop("Set the next placement ID to use in placement creation."),
gettext_noop("Placement IDs are normally generated using a sequence. If "
"next_placement_id is set to a non-zero value, placement IDs will "
"instead be generated by incrementing from the value of "
"this GUC and this will be reflected in the GUC. This is "
"mainly useful to ensure consistent placement IDs when running "
"tests in parallel."),
&NextPlacementId,
0, 0, INT_MAX,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.max_task_string_size",
gettext_noop("Sets the maximum size (in bytes) of a worker task call string."),
gettext_noop("Active worker tasks' are tracked in a shared hash table "
"on the master node. This configuration value limits the "
"maximum size of an individual worker task, and "
"affects the size of pre-allocated shared memory."),
&MaxTaskStringSize,
12288, 8192, 65536,
PGC_POSTMASTER,
0,
NULL, NULL, NULL);
DefineCustomBoolVariable(
"citus.enable_statistics_collection",
gettext_noop("Enables sending basic usage statistics to Citus."),
gettext_noop("Citus uploads daily anonymous usage reports containing "
"rounded node count, shard size, distributed table count, "
"and operating system name. This configuration value controls "
"whether these reports are sent."),
&EnableStatisticsCollection,
#if defined(HAVE_LIBCURL) && defined(ENABLE_CITUS_STATISTICS_COLLECTION)
true,
#else
false,
#endif
PGC_SIGHUP,
GUC_SUPERUSER_ONLY,
&StatisticsCollectionGucCheckHook,
NULL, NULL);
DefineCustomStringVariable(
"citus.node_conninfo",
gettext_noop("Sets parameters used for outbound connections."),
NULL,
&NodeConninfo,
#ifdef USE_SSL
"sslmode=require",
#else
"sslmode=prefer",
#endif
PGC_SIGHUP,
GUC_SUPERUSER_ONLY,
NodeConninfoGucCheckHook,
NodeConninfoGucAssignHook,
NULL);
DefineCustomIntVariable(
"citus.isolation_test_session_remote_process_id",
NULL,
NULL,
&IsolationTestSessionRemoteProcessID,
-1, -1, INT_MAX,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
DefineCustomIntVariable(
"citus.isolation_test_session_process_id",
NULL,
NULL,
&IsolationTestSessionProcessID,
-1, -1, INT_MAX,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
NormalizeWorkerListPath();
/* warn about config items in the citus namespace that are not registered above */
EmitWarningsOnPlaceholders("citus");
}
/*
* We don't want to allow values less than 1.0. However, we define -1 as the value to disable
* distributed deadlock checking. Here we enforce our special constraint.
*/
static bool
ErrorIfNotASuitableDeadlockFactor(double *newval, void **extra, GucSource source)
{
if (*newval <= 1.0 && *newval != -1.0)
{
ereport(WARNING, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg(
"citus.distributed_deadlock_detection_factor cannot be less than 1. "
"To disable distributed deadlock detection set the value to -1.")));
return false;
}
return true;
}
/*
* NormalizeWorkerListPath converts the path configured via
* citus.worker_list_file into an absolute path, falling back to the default
* value if necessary. The previous value of the config variable is
* overwritten with the normalized value.
*
* NB: This has to be called before ChangeToDataDir() is called as otherwise
* the relative paths won't make much sense to the user anymore.
*/
static void
NormalizeWorkerListPath(void)
{
char *absoluteFileName = NULL;
if (WorkerListFileName != NULL)
{
absoluteFileName = make_absolute_path(WorkerListFileName);
}
else if (DataDir != NULL)
{
absoluteFileName = malloc(strlen(DataDir) + strlen(WORKER_LIST_FILENAME) + 2);
if (absoluteFileName == NULL)
{
ereport(FATAL, (errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
}
sprintf(absoluteFileName, "%s/%s", DataDir, WORKER_LIST_FILENAME);
}
else
{
ereport(FATAL, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("%s does not know where to find the \"worker_list_file\" "
"configuration file.\n"
"This can be specified as \"citus.worker_list_file\" in "
"\"%s\", or by the -D invocation option, or by the PGDATA "
"environment variable.\n", progname, ConfigFileName)));
}
SetConfigOption("citus.worker_list_file", absoluteFileName, PGC_POSTMASTER,
PGC_S_OVERRIDE);
free(absoluteFileName);
}
/*
* NodeConninfoGucCheckHook ensures conninfo settings are in the expected form
* and that the keywords of all non-null settings are on a whitelist devised to
* keep users from setting options that may result in confusion.
*/
static bool
NodeConninfoGucCheckHook(char **newval, void **extra, GucSource source)
{
/* this array _must_ be kept in an order usable by bsearch */
const char *whitelist[] = {
"application_name",
"connect_timeout",
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
"gsslib",
#endif
"keepalives",
"keepalives_count",
"keepalives_idle",
"keepalives_interval",
#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
"krbsrvname",
#endif
"sslcompression",
"sslcrl",
"sslmode",
"sslrootcert"
};
char *errorMsg = NULL;
bool conninfoValid = CheckConninfo(*newval, whitelist, lengthof(whitelist),
&errorMsg);
if (!conninfoValid)
{
GUC_check_errdetail("%s", errorMsg);
}
return conninfoValid;
}
/*
* NodeConninfoGucAssignHook is the assignment hook for the node_conninfo GUC
* variable. Though this GUC is a "string", we actually parse it as a non-URI
* PQconninfo key/value setting, storing the resultant PQconninfoOption values
* using the public functions in connection_configuration.c.
*/
static void
NodeConninfoGucAssignHook(const char *newval, void *extra)
{
PQconninfoOption *optionArray = NULL;
PQconninfoOption *option = NULL;
if (newval == NULL)
{
newval = "";
}
optionArray = PQconninfoParse(newval, NULL);
if (optionArray == NULL)
{
ereport(FATAL, (errmsg("cannot parse node_conninfo value"),
errdetail("The GUC check hook should prevent "
"all malformed values.")));
}
ResetConnParams();
for (option = optionArray; option->keyword != NULL; option++)
{
if (option->val == NULL || option->val[0] == '\0')
{
continue;
}
AddConnParam(option->keyword, option->val);
}
PQconninfoFree(optionArray);
}
static bool
StatisticsCollectionGucCheckHook(bool *newval, void **extra, GucSource source)
{
#ifdef HAVE_LIBCURL
return true;
#else
/* if libcurl is not installed, only accept false */
if (*newval)
{
GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
GUC_check_errdetail("Citus was compiled without libcurl support.");
return false;
}
else
{
return true;
}
#endif
}
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