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Commitd2d5401

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1 parent8c21867 commitd2d5401

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‎repeater.c

Lines changed: 63 additions & 72 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,14 @@
1-
/*
1+
/*-------------------------------------------------------------------------
2+
*
23
* repeater.c
4+
* Simple demo for remote plan execution patch.
35
*
6+
* Transfer query plan to a remote instance and wait for result.
7+
* Remote instance parameters (host, port) defines by GUCs.
8+
*
9+
* Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
10+
* Portions Copyright (c) 2018-2019, Postgres Professional
11+
*-------------------------------------------------------------------------
412
*/
513

614
#include"postgres.h"
@@ -11,12 +19,9 @@
1119
#include"fmgr.h"
1220
#include"libpq/libpq.h"
1321
#include"libpq-fe.h"
14-
#include"nodes/params.h"
1522
#include"optimizer/planner.h"
1623
#include"tcop/utility.h"
1724
#include"utils/guc.h"
18-
#include"utils/memutils.h"
19-
#include"utils/plancache.h"
2025

2126
PG_MODULE_MAGIC;
2227

@@ -32,12 +37,14 @@ static void HOOK_Utility_injection(PlannedStmt *pstmt, const char *queryString,
3237
char*completionTag);
3338
staticvoidHOOK_ExecStart_injection(QueryDesc*queryDesc,inteflags);
3439
staticvoidHOOK_ExecEnd_injection(QueryDesc*queryDesc);
35-
staticintexecute_query(PGconn*dest,QueryDesc*queryDesc,inteflags);
36-
3740

41+
/* Remote instance parameters. */
3842
char*repeater_host_name;
3943
intrepeater_port_number;
4044

45+
staticboolExtensionIsActivated= false;
46+
staticPGconn*conn=NULL;
47+
4148
/*
4249
* Module load/unload callback
4350
*/
@@ -79,8 +86,6 @@ _PG_init(void)
7986
ExecutorEnd_hook=HOOK_ExecEnd_injection;
8087
}
8188

82-
staticPGconn*conn=NULL;
83-
8489
staticPGconn*
8590
EstablishConnection(void)
8691
{
@@ -90,17 +95,17 @@ EstablishConnection(void)
9095
returnconn;
9196

9297
/* Connect to slave and send it a query plan */
93-
sprintf(conninfo,"host=localhost port=5433%c",'\0');
98+
sprintf(conninfo,"host=%s port=%d %c",repeater_host_name,repeater_port_number,'\0');
9499
conn=PQconnectdb(conninfo);
95100

96101
if (PQstatus(conn)==CONNECTION_BAD)
97102
elog(LOG,"Connection error. conninfo: %s",conninfo);
103+
else
104+
elog(LOG,"Connection established: host=%s, port=%d",repeater_host_name,repeater_port_number);
98105

99106
returnconn;
100107
}
101108

102-
staticboolExtensionIsActivated= false;
103-
104109
staticbool
105110
ExtensionIsActive(void)
106111
{
@@ -117,6 +122,10 @@ ExtensionIsActive(void)
117122
returnExtensionIsActivated;
118123
}
119124

125+
/*
126+
* We need to send some DML queries for sync database schema to a plan execution
127+
* at a remote instance.
128+
*/
120129
staticvoid
121130
HOOK_Utility_injection(PlannedStmt*pstmt,
122131
constchar*queryString,
@@ -126,27 +135,35 @@ HOOK_Utility_injection(PlannedStmt *pstmt,
126135
DestReceiver*dest,
127136
char*completionTag)
128137
{
129-
Node*parsetree=pstmt->utilityStmt;
138+
Node*parsetree=pstmt->utilityStmt;
139+
PGresult*result;
130140

141+
/*
142+
* Very non-trivial decision about transferring utility query to data nodes.
143+
* This exception list used for demonstration and let us to execute some
144+
* simple queries.
145+
*/
131146
if (ExtensionIsActive()&&
147+
pstmt->canSetTag&&
132148
(nodeTag(parsetree)!=T_CopyStmt)&&
133149
(nodeTag(parsetree)!=T_CreateExtensionStmt)&&
134150
(nodeTag(parsetree)!=T_ExplainStmt)&&
151+
(nodeTag(parsetree)!=T_FetchStmt)&&
135152
(context!=PROCESS_UTILITY_SUBCOMMAND)
136153
)
137154
{
138-
PGresult*result;
139-
155+
/*
156+
* Previous query could be completed with error report at this instance.
157+
* In this case, we need to prepare connection to the remote instance.
158+
*/
140159
while ((result=PQgetResult(EstablishConnection()))!=NULL);
141160

142161
if (PQsendQuery(EstablishConnection(),queryString)==0)
143-
{
144-
elog(ERROR,"Sending UTILITY query error: %s",queryString);
145-
PQreset(conn);
146-
}
162+
elog(ERROR,"Connection error: query: %s, status=%d, errmsg=%s",
163+
queryString,
164+
PQstatus(EstablishConnection()),
165+
PQerrorMessage(EstablishConnection()));
147166
}
148-
else
149-
elog(LOG,"UTILITY query without sending: %s",queryString);
150167

151168
if (next_ProcessUtility_hook)
152169
(*next_ProcessUtility_hook) (pstmt,queryString,context,params,
@@ -156,48 +173,51 @@ HOOK_Utility_injection(PlannedStmt *pstmt,
156173
context,params,queryEnv,
157174
dest,completionTag);
158175

176+
/*
177+
* Check end of query execution at the remote instance.
178+
*/
159179
if (conn)
160-
{
161-
PGresult*result;
162-
163180
while ((result=PQgetResult(conn))!=NULL);
164-
}
165181
}
166-
staticintIsExecuted=0;
167182

168183
staticvoid
169184
HOOK_ExecStart_injection(QueryDesc*queryDesc,inteflags)
170185
{
171-
Node*parsetree=queryDesc->plannedstmt->utilityStmt;
186+
Node*parsetree=queryDesc->plannedstmt->utilityStmt;
187+
PGresult*result;
188+
PGconn*dest=EstablishConnection();
172189

173190
if (prev_ExecutorStart)
174191
prev_ExecutorStart(queryDesc,eflags);
175192
else
176193
standard_ExecutorStart(queryDesc,eflags);
177-
178-
IsExecuted++;
179-
180-
if (IsExecuted>1)
181-
return;
182-
183-
if (
184-
ExtensionIsActive()&&
185-
(repeater_host_name==0)&&
186-
((parsetree==NULL)|| (nodeTag(parsetree)!=T_CreatedbStmt))&&
187-
!(eflags&EXEC_FLAG_EXPLAIN_ONLY)
188-
)
194+
elog(LOG,"QUERY: %s",queryDesc->sourceText);
195+
/*
196+
* This not fully correct sign for prevent passing each subquery to
197+
* the remote instance. Only for demo.
198+
*/
199+
if (ExtensionIsActive()&&
200+
queryDesc->plannedstmt->canSetTag&&
201+
((parsetree==NULL)|| (nodeTag(parsetree)!=T_CreatedbStmt))&&
202+
!(eflags&EXEC_FLAG_EXPLAIN_ONLY))
189203
{
190-
elog(LOG,"Send query: %s",queryDesc->sourceText);
191-
if (execute_query(EstablishConnection(),queryDesc,eflags)==0)
192-
PQreset(conn);
204+
/*
205+
* Prepare connection.
206+
*/
207+
while ((result=PQgetResult(dest))!=NULL);
208+
elog(LOG,"->QUERY: %s",queryDesc->sourceText);
209+
if (PQsendPlan(dest,serialize_plan(queryDesc,eflags))==0)
210+
/*
211+
* Report about remote execution error.
212+
*/
213+
elog(ERROR,"Connection errors during PLAN transferring: status=%d, errmsg=%s",
214+
PQstatus(dest),PQerrorMessage(dest));
193215
}
194216
}
195217

196218
staticvoid
197219
HOOK_ExecEnd_injection(QueryDesc*queryDesc)
198220
{
199-
IsExecuted--;
200-
/* Execute before hook because it destruct memory context of exchange list */
201221
if (conn)
202222
{
203223
PGresult*result;
@@ -210,32 +230,3 @@ HOOK_ExecEnd_injection(QueryDesc *queryDesc)
210230
else
211231
standard_ExecutorEnd(queryDesc);
212232
}
213-
214-
215-
/*
216-
* Serialize plan and send it to the destination instance
217-
*/
218-
staticint
219-
execute_query(PGconn*dest,QueryDesc*queryDesc,inteflags)
220-
{
221-
PGresult*result;
222-
223-
Assert(dest!=NULL);
224-
225-
/*
226-
* Before send of plan we need to check connection state.
227-
* If previous query was failed, we get PGRES_FATAL_ERROR.
228-
*/
229-
while ((result=PQgetResult(dest))!=NULL);
230-
231-
if (PQsendPlan(dest,serialize_plan(queryDesc,eflags))==0)
232-
{
233-
/*
234-
* Report about remote execution error and return control to caller.
235-
*/
236-
elog(ERROR,"PLAN sending error.");
237-
return0;
238-
}
239-
240-
return1;
241-
}

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