mirror of https://github.com/citusdata/citus.git
110 lines
4.2 KiB
C
110 lines
4.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* master_protocol.h
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* Header for shared declarations for access to master node data. These data
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* are used to create new shards or update existing ones.
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*
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* Copyright (c) 2012-2016, Citus Data, Inc.
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*
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* $Id$
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef MASTER_PROTOCOL_H
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#define MASTER_PROTOCOL_H
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#include "fmgr.h"
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#include "nodes/pg_list.h"
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/*
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* In our distributed database, we need a mechanism to make remote procedure
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* calls between clients, the master node, and worker nodes. These remote calls
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* require serializing and deserializing values and function signatures between
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* nodes; and for these, we currently use PostgreSQL's built-in type and
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* function definition system. This approach is by no means ideal however; and
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* our implementation: (i) cannot perform compile-time type checks, (ii)
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* requires additional effort when upgrading to new function signatures, and
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* (iii) hides argument and return value names and types behind complicated
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* pg_proc.h definitions.
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*
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* An ideal implementation should overcome these problems, and make it much
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* easier to pass values back and forth between nodes. One such implementation
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* that comes close to ideal is Google's Protocol Buffers. Nonetheless, we do
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* not use it in here as its inclusion requires changes to PostgreSQL's make
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* system, and a native C version is currently unavailable.
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*/
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/* Number of tuple fields that master node functions return */
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#define TABLE_METADATA_FIELDS 7
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#define CANDIDATE_NODE_FIELDS 2
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#define WORKER_NODE_FIELDS 2
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/* Name of columnar foreign data wrapper */
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#define CSTORE_FDW_NAME "cstore_fdw"
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/* ShardId sequence name as defined in initdb.c */
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#define SHARDID_SEQUENCE_NAME "pg_dist_shardid_seq"
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/* Remote call definitions to help with data staging and deletion */
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#define WORKER_APPLY_SHARD_DDL_COMMAND \
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"SELECT worker_apply_shard_ddl_command (" UINT64_FORMAT ", %s)"
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#define WORKER_APPEND_TABLE_TO_SHARD \
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"SELECT worker_append_table_to_shard (%s, %s, %s, %u)"
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#define SHARD_MIN_VALUE_QUERY "SELECT min(%s) FROM %s"
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#define SHARD_MAX_VALUE_QUERY "SELECT max(%s) FROM %s"
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#define SHARD_TABLE_SIZE_QUERY "SELECT pg_table_size('%s')"
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#define SHARD_CSTORE_TABLE_SIZE_QUERY "SELECT cstore_table_size('%s')"
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#define DROP_REGULAR_TABLE_COMMAND "DROP TABLE IF EXISTS %s"
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#define DROP_FOREIGN_TABLE_COMMAND "DROP FOREIGN TABLE IF EXISTS %s"
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#define CREATE_SCHEMA_COMMAND "CREATE SCHEMA IF NOT EXISTS %s"
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/* Enumeration that defines the shard placement policy to use while staging */
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typedef enum
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{
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SHARD_PLACEMENT_INVALID_FIRST = 0,
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SHARD_PLACEMENT_LOCAL_NODE_FIRST = 1,
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SHARD_PLACEMENT_ROUND_ROBIN = 2
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} ShardPlacementPolicyType;
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/* Config variables managed via guc.c */
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extern int ShardReplicationFactor;
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extern int ShardMaxSize;
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extern int ShardPlacementPolicy;
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/* Function declarations local to the distributed module */
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extern bool CStoreTable(Oid relationId);
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extern Oid ResolveRelationId(text *relationName);
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extern List * GetTableDDLEvents(Oid relationId);
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extern void CheckDistributedTable(Oid relationId);
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extern void CreateShardPlacements(int64 shardId, List *ddlEventList,
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List *workerNodeList, int workerStartIndex,
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int replicationFactor);
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/* Function declarations for generating metadata for shard creation */
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extern Datum get_table_metadata(PG_FUNCTION_ARGS);
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extern Datum get_table_ddl_events(PG_FUNCTION_ARGS);
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extern Datum get_new_shardid(PG_FUNCTION_ARGS);
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extern Datum get_local_first_candidate_nodes(PG_FUNCTION_ARGS);
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extern Datum get_round_robin_candidate_nodes(PG_FUNCTION_ARGS);
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extern Datum get_active_worker_nodes(PG_FUNCTION_ARGS);
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/* Function declarations to help with data staging and deletion */
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extern Datum create_empty_shard(PG_FUNCTION_ARGS);
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extern Datum append_table_to_shard(PG_FUNCTION_ARGS);
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extern Datum apply_delete_command(PG_FUNCTION_ARGS);
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extern Datum drop_all_shards(PG_FUNCTION_ARGS);
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/* function declarations for shard creation functionality */
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extern Datum create_worker_shards(PG_FUNCTION_ARGS);
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/* function declarations for shard repair functionality */
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extern Datum copy_shard_placement(PG_FUNCTION_ARGS);
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#endif /* MASTER_PROTOCOL_H */
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