Fix some more master->coordinator comments

src/backend/distributed/commands/README.md

@@ -44,11 +44,3 @@ TODO: to be written by someone with enough knowledge to write how, when and why
 Implemented in `multi_copy.c`
 
 TODO: to be written by someone with enough knowledge to write how, when and why it is used.
-
-## MASTER_HOST host
-
-Implemented in `multi_copy.c`
-
-Triggered by the `MASTER_HOST` option being set on the copy command. Also accepts `MASTER_PORT`
-
-TODO: to be written by someone with enough knowledge to write how, when and why it is used.

src/backend/distributed/commands/index.c

@@ -102,7 +102,7 @@ IsIndexRenameStmt(RenameStmt *renameStmt)
  * PreprocessIndexStmt determines whether a given CREATE INDEX statement involves
  * a distributed table. If so (and if the statement does not use unsupported
  * options), it modifies the input statement to ensure proper execution against
- * the master node table and creates a DDLJob to encapsulate information needed
+ * the coordinator node table and creates a DDLJob to encapsulate information needed
  * during the worker node portion of DDL execution before returning that DDLJob
  * in a List. If no distributed table is involved, this function returns NIL.
  */
@@ -194,7 +194,7 @@ PreprocessIndexStmt(Node *node, const char *createIndexCommand)
  * PreprocessReindexStmt determines whether a given REINDEX statement involves
  * a distributed table. If so (and if the statement does not use unsupported
  * options), it modifies the input statement to ensure proper execution against
- * the master node table and creates a DDLJob to encapsulate information needed
+ * the coordinator node table and creates a DDLJob to encapsulate information needed
  * during the worker node portion of DDL execution before returning that DDLJob
  * in a List. If no distributed table is involved, this function returns NIL.
  */
@@ -302,7 +302,7 @@ PreprocessReindexStmt(Node *node, const char *reindexCommand)
  * PreprocessDropIndexStmt determines whether a given DROP INDEX statement involves
  * a distributed table. If so (and if the statement does not use unsupported
  * options), it modifies the input statement to ensure proper execution against
- * the master node table and creates a DDLJob to encapsulate information needed
+ * the coordinator node table and creates a DDLJob to encapsulate information needed
  * during the worker node portion of DDL execution before returning that DDLJob
  * in a List. If no distributed table is involved, this function returns NIL.
  */

src/backend/distributed/executor/adaptive_executor.c

@@ -4498,7 +4498,7 @@ ExtractParametersFromParamList(ParamListInfo paramListInfo,
 
 		/*
 		 * Use 0 for data types where the oid values can be different on
-		 * the master and worker nodes. Therefore, the worker nodes can
+		 * the coordinator and worker nodes. Therefore, the worker nodes can
 		 * infer the correct oid.
 		 */
 		if (parameterData->ptype >= FirstNormalObjectId && !useOriginalCustomTypeOids)

src/backend/distributed/planner/extended_op_node_utils.c

@@ -311,8 +311,8 @@ PartitionColumnInTableList(Var *column, List *tableNodeList)
 
 /*
  * ShouldPullDistinctColumn returns true if distinct aggregate should pull
- * individual columns from worker to master and evaluate aggregate operation
- * at master.
+ * individual columns from worker to coordinator and evaluate aggregate operation
+ * on the coordinator.
  *
  * Pull cases are:
  * - repartition subqueries

src/backend/distributed/planner/multi_explain.c

@@ -167,7 +167,7 @@ PG_FUNCTION_INFO_V1(worker_save_query_explain_analyze);
 
 /*
  * CitusExplainScan is a custom scan explain callback function which is used to
- * print explain information of a Citus plan which includes both master and
+ * print explain information of a Citus plan which includes both combine query and
  * distributed plan.
  */
 void

src/backend/distributed/planner/planner_readme.md

@@ -46,7 +46,7 @@ The join order planner is applied to the join tree in the original query and gen
 
 The logical optimizer uses commutativity rules to push project and select operators down below the `MultiCollect` nodes. Everything above the `MultiCollect` operator will be is executed on the coordinator and everything below on the workers. Additionally, the optimizer uses distributivity rules to push down operators below the `MultiJoin` nodes, such that filters and projections are applied prior to joins. This is primarily relevant for re-partition joins which first try to reduce the data by applying selections and projections, and then re-partitioning the result.
 
-A number of SQL clauses like aggregates, GROUP BY, ORDER BY, LIMIT can only be pushed down below the `MultiCollect` under certain conditions. All these clauses are bundled together in a `MultiExtendedOpNode`. After the basic transformation, the `MultiExtendedOpNode`s are directly above the `MultiCollect` nodes. They are then split into a master and a worker part and the worker part is pushed down below the `MultiCollect`.
+A number of SQL clauses like aggregates, GROUP BY, ORDER BY, LIMIT can only be pushed down below the `MultiCollect` under certain conditions. All these clauses are bundled together in a `MultiExtendedOpNode`. After the basic transformation, the `MultiExtendedOpNode`s are directly above the `MultiCollect` nodes. They are then split into a coordinator and a worker part and the worker part is pushed down below the `MultiCollect`.
 
 ### Physical planner
 

src/include/distributed/combine_query_planner.h

@@ -23,7 +23,7 @@
 #endif
 
 
-/* Function declarations for building local plans on the master node */
+/* Function declarations for building local plans on the coordinator node */
 struct DistributedPlan;
 struct CustomScan;
 extern Path * CreateCitusCustomScanPath(PlannerInfo *root, RelOptInfo *relOptInfo,

src/include/distributed/coordinator_protocol.h

@@ -24,7 +24,7 @@
 
 /*
  * In our distributed database, we need a mechanism to make remote procedure
- * calls between clients, the master node, and worker nodes. These remote calls
+ * calls between clients, the coordinator node, and worker nodes. These remote calls
  * require serializing and deserializing values and function signatures between
  * nodes; and for these, we currently use PostgreSQL's built-in type and
  * function definition system. This approach is by no means ideal however; and
@@ -41,7 +41,7 @@
  */
 
 
-/* Number of tuple fields that master node functions return */
+/* Number of tuple fields that coordinator node functions return */
 #define TABLE_METADATA_FIELDS 7
 #define CANDIDATE_NODE_FIELDS 2
 #define WORKER_NODE_FIELDS 2

src/include/distributed/distributed_planner.h

@@ -163,12 +163,13 @@ typedef struct DistributedPlanningContext
 
 
 /*
- * CitusCustomScanPath is injected into the planner during the master query planning phase
- * of the logical planner.
- * We call out to the standard planner to plan the master query part for the output of the
- * logical planner. This makes it easier to implement new sql features into the logical
- * planner by not having to manually implement the plan creation for the query on the
- * master.
+ * CitusCustomScanPath is injected into the planner during the combine query planning
+ * phase of the logical planner.
+ *
+ * We call out to the standard planner to plan the combine query part for the output of
+ * the logical planner. This makes it easier to implement new sql features into the
+ * logical planner by not having to manually implement the plan creation for the combine
+ * query on the coordinator..
  */
 typedef struct CitusCustomScanPath
 {
@@ -176,7 +177,7 @@ typedef struct CitusCustomScanPath
 
 	/*
 	 * Custom scan node computed by the citus planner that will produce the tuples for the
-	 * path we are injecting during the planning of the master query
+	 * path we are injecting during the planning of the combine query
 	 */
 	CustomScan *remoteScan;
 } CitusCustomScanPath;

src/include/distributed/extended_op_node_utils.h

@@ -15,7 +15,7 @@
 
 /*
  * ExtendedOpNodeProperties is a helper structure that is used to
- * share the common information among the worker and master extended
+ * share the common information among the worker and coordinator extended
  * op nodes.
  *
  * It is designed to be a read-only singleton object per extended op node

src/include/distributed/metadata_utility.h

@@ -1,8 +1,8 @@
 /*-------------------------------------------------------------------------
  *
  * metadata_utility.h
- *	  Type and function declarations used for reading and modifying master
- *    node's metadata.
+ *	  Type and function declarations used for reading and modifying
+ *    coordinator node's metadata.
  *
  * Copyright (c) Citus Data, Inc.
  *

src/include/distributed/multi_logical_planner.h

@@ -156,7 +156,7 @@ typedef struct MultiCartesianProduct
 /*
  * MultiExtendedOp defines a set of extended operators that operate on columns
  * in relational algebra. This node allows us to distinguish between operations
- * in the master and worker nodes, and also captures the following:
+ * in the coordinator and worker nodes, and also captures the following:
  *
  * (1) Aggregate functions such as sums or averages;
  * (2) Grouping of attributes; these groupings may also be tied to aggregates;

src/include/distributed/multi_server_executor.h

@@ -58,7 +58,7 @@ typedef enum
 } TaskExecStatus;
 
 
-/* Enumeration to track file transmits to the master node */
+/* Enumeration to track file transmits to the coordinator node */
 typedef enum
 {
 	EXEC_TRANSMIT_INVALID_FIRST = 0,

src/include/distributed/pg_dist_placement.h

@@ -4,9 +4,9 @@
  *	  definition of the "server" relation (pg_dist_placement).
  *
  * This table keeps information on remote shards and their whereabouts on the
- * master node. The table's contents are updated and used as follows: (i) the
+ * coordinator node. The table's contents are updated and used as follows: (i) the
  * worker nodes send periodic reports about the shards they contain, and (ii)
- * the master reconciles these shard reports, and determines outdated, under-
+ * the coordinator reconciles these shard reports, and determines outdated, under-
  * and over-replicated shards.
  *
  * Copyright (c) Citus Data, Inc.