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Add dbmirror to /contrib. Minor C cleanups and Makefile.

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Steven Singer
This commit is contained in:
Bruce Momjian 2002-06-23 21:58:08 +00:00
parent 5a15149736
commit d64b97ae37
10 changed files with 2046 additions and 1 deletions
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2
contrib/dblink/Makefile
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# $Header: /cvsroot/pgsql/contrib/dblink/Makefile,v 1.4 2001/09/06 10:49:29 petere Exp $ # $Header: /cvsroot/pgsql/contrib/dblink/Makefile,v 1.5 2002/06/23 21:58:07 momjian Exp $
subdir = contrib/dblink subdir = contrib/dblink
top_builddir = ../.. top_builddir = ../..

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contrib/dbmirror/AddTrigger.sql Normal file
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CREATE TRIGGER "MyTableName_Trig" AFTER INSERT OR DELETE OR UPDATE
ON "MyTableName" FOR EACH ROW EXECUTE PROCEDURE
"recordchange" ();

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contrib/dbmirror/COPYING Normal file
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869
contrib/dbmirror/DBMirror.pl Executable file
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#!/usr/bin/perl
#############################################################################
#
# DBMirror.pl
# Contains the Database mirroring script.
# This script queries the pending table off the database specified
# (along with the associated schema) for updates that are pending on a
# specific host. The database on that host is then updated with the changes.
#
#
# Written by Steven Singer (ssinger@navtechinc.com)
# (c) 2001-2002 Navtech Systems Support Inc.
# Released under the GNU Public License version 2. See COPYING.
#
#
# 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
# GNU General Public License for more details.
#
##############################################################################
# $Id: DBMirror.pl,v 1.1 2002/06/23 21:58:07 momjian Exp $
#
##############################################################################
=head1 NAME
DBMirror.pl - A Perl module to mirror database changes from a master database
to a slave.
=head1 SYNPOSIS
DBMirror.pl slaveConfigfile.conf
=head1 DESCRIPTION
This Perl script will connect to the master database and query its pending
table for a list of pending changes.
The transactions of the original changes to the master will be preserved
when sending things to the slave.
=cut
=head1 METHODS
=over 4
=cut
BEGIN {
# add in a global path to files
# Pg should be included.
}
use strict;
use Pg;
use IO::Handle;
sub mirrorCommand($$$$$$);
sub mirrorInsert($$$$$);
sub mirrorDelete($$$$$);
sub mirrorUpdate($$$$$);
sub sendQueryToSlaves($$);
sub logErrorMessage($);
sub openSlaveConnection($);
sub updateMirrorHostTable($$);
sub extractData($$);
local $::masterHost;
local $::masterDb;
local $::masterUser;
local $::masterPassword;
local $::errorThreshold=5;
local $::errorEmailAddr=undef;
my %slaveInfoHash;
local $::slaveInfo = \%slaveInfoHash;
my $lastErrorMsg;
my $repeatErrorCount=0;
my $lastXID;
my $commandCount=0;
my $masterConn;
Main();
sub Main() {
#run the configuration file.
if ($#ARGV != 0) {
die "usage: DBMirror.pl configFile\n";
}
if( ! defined do $ARGV[0]) {
logErrorMessage("Invalid Configuration file $ARGV[0]");
die;
}
my $connectString = "host=$::masterHost dbname=$::masterDb user=$::masterUser password=$::masterPassword";
$masterConn = Pg::connectdb($connectString);
unless($masterConn->status == PGRES_CONNECTION_OK) {
logErrorMessage("Can't connect to master database\n" .
$masterConn->errorMessage);
die;
}
my $firstTime = 1;
while(1) {
if($firstTime == 0) {
sleep 60;
}
$firstTime = 0;
# Open up the connection to the slave.
if(! defined $::slaveInfo->{"status"} ||
$::slaveInfo->{"status"} == -1) {
openSlaveConnection($::slaveInfo);
}
sendQueryToSlaves(undef,"SET TRANSACTION ISOLATION LEVEL SERIALIZABLE");
sendQueryToSlaves(undef,"SET CONSTRAINTS ALL DEFERRED");
#Obtain a list of pending transactions using ordering by our approximation
#to the commit time. The commit time approximation is taken to be the
#SeqId of the last row edit in the transaction.
my $pendingTransQuery = "SELECT pd.\"XID\",MAX(\"SeqId\") FROM \"Pending\" pd";
$pendingTransQuery .= " LEFT JOIN \"MirroredTransaction\" mt INNER JOIN";
$pendingTransQuery .= " \"MirrorHost\" mh ON mt.\"MirrorHostId\" = ";
$pendingTransQuery .= " mh.\"MirrorHostId\" AND mh.\"HostName\"=";
$pendingTransQuery .= " '$::slaveInfo->{\"slaveHost\"}' ";
$pendingTransQuery .= " ON pd.\"XID\"";
$pendingTransQuery .= " = mt.\"XID\" WHERE mt.\"XID\" is null ";
$pendingTransQuery .= " GROUP BY pd.\"XID\" ";
$pendingTransQuery .= " ORDER BY MAX(pd.\"SeqId\")";
my $pendingTransResults = $masterConn->exec($pendingTransQuery);
unless($pendingTransResults->resultStatus==PGRES_TUPLES_OK) {
logErrorMessage("Can't query pending table\n" . $masterConn->errorMessage);
die;
}
my $numPendingTrans = $pendingTransResults->ntuples;
my $curTransTuple = 0;
#
# This loop loops through each pending transaction in the proper order.
# The Pending row edits for that transaction will be queried from the
# master and sent + committed to the slaves.
while($curTransTuple < $numPendingTrans) {
my $XID = $pendingTransResults->getvalue($curTransTuple,0);
my $maxSeqId = $pendingTransResults->getvalue($curTransTuple,1);
my $seqId;
my $pendingQuery = "SELECT pnd.\"SeqId\",pnd.\"TableName\",";
$pendingQuery .= " pnd.\"Op\",pnddata.\"IsKey\", pnddata.\"Data\" AS \"Data\" ";
$pendingQuery .= " FROM \"Pending\" pnd, \"PendingData\" pnddata ";
$pendingQuery .= " WHERE pnd.\"SeqId\" = pnddata.\"SeqId\" AND ";
$pendingQuery .= " pnd.\"XID\"=$XID ORDER BY \"SeqId\", \"IsKey\" DESC";
my $pendingResults = $masterConn->exec($pendingQuery);
unless($pendingResults->resultStatus==PGRES_TUPLES_OK) {
logErrorMessage("Can't query pending table\n" . $masterConn->errorMessage);
die;
}
my $numPending = $pendingResults->ntuples;
my $curTuple = 0;
sendQueryToSlaves(undef,"BEGIN");
while ($curTuple < $numPending) {
$seqId = $pendingResults->getvalue($curTuple,0);
my $tableName = $pendingResults->getvalue($curTuple,1);
my $op = $pendingResults->getvalue($curTuple,2);
$curTuple = mirrorCommand($seqId,$tableName,$op,$XID,
$pendingResults,$curTuple) +1;
if($::slaveInfo->{"status"}==-1) {
last;
}
}
#Now commit the transaction.
if($::slaveInfo->{"status"}==-1) {
last;
}
sendQueryToSlaves(undef,"COMMIT");
updateMirrorHostTable($XID,$seqId);
if($commandCount > 5000) {
$commandCount = 0;
$::slaveInfo->{"status"} = -1;
$::slaveInfo->{"slaveConn"}->reset;
#Open the connection right away.
openSlaveConnection($::slaveInfo);
}
$pendingResults = undef;
$curTransTuple = $curTransTuple +1;
}#while transactions left.
$pendingTransResults = undef;
}#while(1)
}#Main
=item mirrorCommand(SeqId,tableName,op,transId,pendingResults,curTuple)
Mirrors a single SQL Command(change to a single row) to the slave.
=over 4
=item * SeqId
The id number of the change to mirror. This is the
primary key of the pending table.
=item * tableName
The name of the table the transaction takes place on.
=item * op
The type of operation this transaction is. 'i' for insert, 'u' for update or
'd' for delete.
=item * transId
The Transaction of of the Transaction that this command is part of.
=item * pendingResults
A Results set structure returned from Pg::execute that contains the
join of the Pending and PendingData tables for all of the pending row
edits in this transaction.
=item * currentTuple
The tuple(or row) number of the pendingRow for the command that is about
to be edited. If the command is an update then this points to the row
with IsKey equal to true. The next row, curTuple+1 is the contains the
PendingData with IsKey false for the update.
=item returns
The tuple number of last tuple for this command. This might be equal to
currentTuple or it might be larger (+1 in the case of an Update).
=back
=cut
sub mirrorCommand($$$$$$) {
my $seqId = $_[0];
my $tableName = $_[1];
my $op = $_[2];
my $transId = $_[3];
my $pendingResults = $_[4];
my $currentTuple = $_[5];
if($op eq 'i') {
$currentTuple = mirrorInsert($seqId,$tableName,$transId,$pendingResults
,$currentTuple);
}
if($op eq 'd') {
$currentTuple = mirrorDelete($seqId,$tableName,$transId,$pendingResults,
$currentTuple);
}
if($op eq 'u') {
$currentTuple = mirrorUpdate($seqId,$tableName,$transId,$pendingResults,
$currentTuple);
}
$commandCount = $commandCount +1;
if($commandCount % 100 == 0) {
# print "Sent 100 commmands on SeqId $seqId \n";
# flush STDOUT;
}
return $currentTuple
}
=item mirrorInsert(transId,tableName,transId,pendingResults,currentTuple)
Mirrors an INSERT operation to the slave database. A new row is placed
in the slave database containing the primary key from pendingKeys along with
the data fields contained in the row identified by sourceOid.
=over 4
=item * transId
The sequence id of the INSERT operation being mirrored. This is the primary
key of the pending table.
=item * tableName
The name of the table the transaction takes place on.
=item * sourceOid
The OID of the row in the master database for which this transaction effects.
If the transaction is a delete then the operation is not valid.
=item * transId
The Transaction Id of transaction that this insert is part of.
=item * pendingResults
A Results set structure returned from Pg::execute that contains the
join of the Pending and PendingData tables for all of the pending row
edits in this transaction.
=item * currentTuple
The tuple(or row) number of the pendingRow for the command that is about
to be edited. In the case of an insert this should point to the one
row for the row edit.
=item returns
The tuple number of the last tuple for the row edit. This should be
currentTuple.
=back
=cut
sub mirrorInsert($$$$$) {
my $seqId = $_[0];
my $tableName = $_[1];
my $transId = $_[2];
my $pendingResults = $_[3];
my $currentTuple = $_[4];
my $counter;
my $column;
my $firstIteration=1;
my %recordValues = extractData($pendingResults,$currentTuple);
#Now build the insert query.
my $insertQuery = "INSERT INTO \"$tableName\" (";
my $valuesQuery = ") VALUES (";
foreach $column (keys (%recordValues)) {
if($firstIteration==0) {
$insertQuery .= " ,";
$valuesQuery .= " ,";
}
$insertQuery .= "\"$column\"";
if(defined $recordValues{$column}) {
my $quotedValue = $recordValues{$column};
$quotedValue =~ s/\\/\\\\/g;
$quotedValue =~ s/'/\\'/g;
$valuesQuery .= "'$quotedValue'";
}
else {
$valuesQuery .= "null";
}
$firstIteration=0;
}
$valuesQuery .= ")";
sendQueryToSlaves(undef,$insertQuery . $valuesQuery);
return $currentTuple;
}
=item mirrorDelete(SeqId,tableName,transId,pendingResult,currentTuple)
Deletes a single row from the slave database. The row is identified by the
primary key for the transaction in the pendingKeys table.
=over 4
=item * SeqId
The Sequence id for this delete request.
=item * tableName
The name of the table to delete the row from.
=item * transId
The Transaction Id of the transaction that this command is part of.
=item * pendingResults
A Results set structure returned from Pg::execute that contains the
join of the Pending and PendingData tables for all of the pending row
edits in this transaction.
=item * currentTuple
The tuple(or row) number of the pendingRow for the command that is about
to be edited. In the case of a delete this should point to the one
row for the row edit.
=item returns
The tuple number of the last tuple for the row edit. This should be
currentTuple.
=back
=cut
sub mirrorDelete($$$$$) {
my $seqId = $_[0];
my $tableName = $_[1];
my $transId = $_[2];
my $pendingResult = $_[3];
my $currentTuple = $_[4];
my %dataHash;
my $currentField;
my $firstField=1;
%dataHash = extractData($pendingResult,$currentTuple);
my $counter=0;
my $deleteQuery = "DELETE FROM \"$tableName\" WHERE ";
foreach $currentField (keys %dataHash) {
if($firstField==0) {
$deleteQuery .= " AND ";
}
my $currentValue = $dataHash{$currentField};
$deleteQuery .= "\"";
$deleteQuery .= $currentField;
if(defined $currentValue) {
$deleteQuery .= "\"='";
$deleteQuery .= $currentValue;
$deleteQuery .= "'";
}
else {
$deleteQuery .= " is null ";
}
$counter++;
$firstField=0;
}
sendQueryToSlaves($transId,$deleteQuery);
return $currentTuple;
}
=item mirrorUpdate(seqId,tableName,transId,pendingResult,currentTuple)
Mirrors over an edit request to a single row of the database.
The primary key from before the edit is used to determine which row in the
slave should be changed.
After the edit takes place on the slave its primary key will match the primary
key the master had immediatly following the edit. All other fields will be set
to the current values.
Data integrity is maintained because the mirroring is performed in an
SQL transcation so either all pending changes are made or none are.
=over 4
=item * seqId
The Sequence id of the update.
=item * tableName
The name of the table to perform the update on.
=item * transId
The transaction Id for the transaction that this command is part of.
=item * pendingResults
A Results set structure returned from Pg::execute that contains the
join of the Pending and PendingData tables for all of the pending row
edits in this transaction.
=item * currentTuple
The tuple(or row) number of the pendingRow for the command that is about
to be edited. In the case of a delete this should point to the one
row for the row edit.
=item returns
The tuple number of the last tuple for the row edit. This should be
currentTuple +1. Which points to the non key row of the update.
=back
=cut
sub mirrorUpdate($$$$$) {
my $seqId = $_[0];
my $tableName = $_[1];
my $transId = $_[2];
my $pendingResult = $_[3];
my $currentTuple = $_[4];
my $counter;
my $quotedValue;
my $updateQuery = "UPDATE \"$tableName\" SET ";
my $currentField;
my %keyValueHash;
my %dataValueHash;
my $firstIteration=1;
#Extract the Key values. This row contains the values of the
# key fields before the update occours(the WHERE clause)
%keyValueHash = extractData($pendingResult,$currentTuple);
#Extract the data values. This is a SET clause that contains
#values for the entire row AFTER the update.
%dataValueHash = extractData($pendingResult,$currentTuple+1);
$firstIteration=1;
foreach $currentField (keys (%dataValueHash)) {
if($firstIteration==0) {
$updateQuery .= ", ";
}
$updateQuery .= " \"$currentField\"=";
my $currentValue = $dataValueHash{$currentField};
if(defined $currentValue ) {
$quotedValue = $currentValue;
$quotedValue =~ s/\\/\\\\/g;
$quotedValue =~ s/'/\\'/g;
$updateQuery .= "'$quotedValue'";
}
else {
$updateQuery .= "null ";
}
$firstIteration=0;
}
$updateQuery .= " WHERE ";
$firstIteration=1;
foreach $currentField (keys (%keyValueHash)) {
my $currentValue;
if($firstIteration==0) {
$updateQuery .= " AND ";
}
$updateQuery .= "\"$currentField\"=";
$currentValue = $keyValueHash{$currentField};
if(defined $currentValue) {
$quotedValue = $currentValue;
$quotedValue =~ s/\\/\\\\/g;
$quotedValue =~ s/'/\\'/g;
$updateQuery .= "'$quotedValue'";
}
else {
$updateQuery .= " null ";
}
$firstIteration=0;
}
sendQueryToSlaves($transId,$updateQuery);
return $currentTuple+1;
}
=item sendQueryToSlaves(seqId,sqlQuery)
Sends an SQL query to the slave.
=over 4
=item * seqId
The sequence Id of the command being sent. Undef if no command is associated
with the query being sent.
=item * sqlQuery
SQL operation to perform on the slave.
=back
=cut
sub sendQueryToSlaves($$) {
my $seqId = $_[0];
my $sqlQuery = $_[1];
if($::slaveInfo->{"status"} == 0) {
my $queryResult = $::slaveInfo->{"slaveConn"}->exec($sqlQuery);
unless($queryResult->resultStatus == PGRES_COMMAND_OK) {
my $errorMessage;
$errorMessage = "Error sending query $seqId to " ;
$errorMessage .= $::slaveInfo->{"slaveHost"};
$errorMessage .=$::slaveInfo->{"slaveConn"}->errorMessage;
$errorMessage .= "\n" . $sqlQuery;
logErrorMessage($errorMessage);
$::slaveInfo->{"slaveConn"}->exec("ROLLBACK");
$::slaveInfo->{"status"} = -1;
}
}
}
=item logErrorMessage(error)
Mails an error message to the users specified $errorEmailAddr
The error message is also printed to STDERR.
=over 4
=item * error
The error message to log.
=back
=cut
sub logErrorMessage($) {
my $error = $_[0];
if(defined $lastErrorMsg and $error eq $lastErrorMsg) {
if($repeatErrorCount<$::errorThreshold) {
$repeatErrorCount++;
warn($error);
return;
}
}
$repeatErrorCount=0;
if(defined $::errorEmailAddr) {
my $mailPipe;
open (mailPipe, "|/bin/mail -s DBMirror.pl $::errorEmailAddr");
print mailPipe "=====================================================\n";
print mailPipe " DBMirror.pl \n";
print mailPipe "\n";
print mailPipe " The DBMirror.pl script has encountred an error. \n";
print mailPipe " It might indicate that either the master database has\n";
print mailPipe " gone down or that the connection to a slave database can\n";
print mailPipe " not be made. \n";
print mailPipe " Process-Id: $$ on $::masterHost database $::masterDb\n";
print mailPipe "\n";
print mailPipe $error;
print mailPipe "\n\n\n=================================================\n";
close mailPipe;
}
warn($error);
$lastErrorMsg = $error;
}
sub openSlaveConnection($) {
my $slavePtr = $_[0];
my $slaveConn;
my $slaveConnString = "host=" . $slavePtr->{"slaveHost"};
$slaveConnString .= " dbname=" . $slavePtr->{"slaveDb"};
$slaveConnString .= " user=" . $slavePtr->{"slaveUser"};
$slaveConnString .= " password=" . $slavePtr->{"slavePassword"};
$slaveConn = Pg::connectdb($slaveConnString);
if($slaveConn->status !=PGRES_CONNECTION_OK) {
my $errorMessage = "Can't connect to slave database " ;
$errorMessage .= $slavePtr->{"slaveHost"} . "\n";
$errorMessage .= $slaveConn->errorMessage;
logErrorMessage($errorMessage);
$slavePtr->{"status"} = -1;
}
else {
$slavePtr->{"slaveConn"} = $slaveConn;
$slavePtr->{"status"} = 0;
#Determine the MirrorHostId for the slave from the master's database
my $resultSet = $masterConn->exec('SELECT "MirrorHostId" FROM '
. ' "MirrorHost" WHERE "HostName"'
. '=\'' . $slavePtr->{"slaveHost"}
. '\'');
if($resultSet->ntuples !=1) {
my $errorMessage .= $slavePtr->{"slaveHost"} ."\n";
$errorMessage .= "Has no MirrorHost entry on master\n";
logErrorMessage($errorMessage);
$slavePtr->{"status"}=-1;
return;
}
$slavePtr->{"MirrorHostId"} = $resultSet->getvalue(0,0);
}
}
=item updateMirrorHostTable(lastTransId,lastSeqId)
Updates the MirroredTransaction table to reflect the fact that
this transaction has been sent to the current slave.
=over 4
=item * lastTransId
The Transaction id for the last transaction that has been succesfully mirrored to
the currently open slaves.
=item * lastSeqId
The Sequence Id of the last command that has been succefully mirrored
=back
=cut
sub updateMirrorHostTable($$) {
my $lastTransId = shift;
my $lastSeqId = shift;
if($::slaveInfo->{"status"}==0) {
my $deleteTransactionQuery;
my $deleteResult;
my $updateMasterQuery = "INSERT INTO \"MirroredTransaction\" ";
$updateMasterQuery .= " (\"XID\",\"LastSeqId\",\"MirrorHostId\")";
$updateMasterQuery .= " VALUES ($lastTransId,$lastSeqId,$::slaveInfo->{\"MirrorHostId\"}) ";
my $updateResult = $masterConn->exec($updateMasterQuery);
unless($updateResult->resultStatus == PGRES_COMMAND_OK) {
my $errorMessage = $masterConn->errorMessage . "\n";
$errorMessage .= $updateMasterQuery;
logErrorMessage($errorMessage);
die;
}
# print "Updated slaves to transaction $lastTransId\n" ;
# flush STDOUT;
#If this transaction has now been mirrored to all mirror hosts
#then it can be deleted.
$deleteTransactionQuery = 'DELETE FROM "Pending" WHERE "XID"='
. $lastTransId . ' AND (SELECT COUNT(*) FROM "MirroredTransaction"'
. ' WHERE "XID"=' . $lastTransId . ')=(SELECT COUNT(*) FROM'
. ' "MirrorHost")';
$deleteResult = $masterConn->exec($deleteTransactionQuery);
if($deleteResult->resultStatus!=PGRES_COMMAND_OK) {
logErrorMessage($masterConn->errorMessage . "\n" .
$deleteTransactionQuery);
die;
}
}
}
sub extractData($$) {
my $pendingResult = $_[0];
my $currentTuple = $_[1];
my $fnumber;
my %valuesHash;
$fnumber = 4;
my $dataField = $pendingResult->getvalue($currentTuple,$fnumber);
while(length($dataField)>0) {
# Extract the field name that is surronded by double quotes
$dataField =~ m/(\".*?\")/s;
my $fieldName = $1;
$dataField = substr $dataField ,length($fieldName);
$fieldName =~ s/\"//g; #Remove the surronding " signs.
if($dataField =~ m/(^= )/s) {
#Matched null
$dataField = substr $dataField , length($1);
$valuesHash{$fieldName}=undef;
}
elsif ($dataField =~ m/(^=\')/s) {
#Has data.
my $value;
$dataField = substr $dataField ,2; #Skip the ='
LOOP: { #This is to allow us to use last from a do loop.
#Recommended in perlsyn manpage.
do {
my $matchString;
#Find the substring ending with the first ' or first \
$dataField =~ m/(.*?[\'\\])?/s;
$matchString = $1;
$value .= substr $matchString,0,length($matchString)-1;
if($matchString =~ m/(\'$)/s) {
# $1 runs to the end of the field value.
$dataField = substr $dataField,length($matchString)+1;
last;
}
else {
#deal with the escape character.
#It The character following the escape gets appended.
$dataField = substr $dataField,length($matchString);
$dataField =~ s/(^.)//s;
$value .= $1;
}
} until(length($dataField)==0);
}
$valuesHash{$fieldName} = $value;
}#else if
else {
logErrorMessage "Error in PendingData Sequence Id " .
$pendingResult->getvalue($currentTuple,0);
die;
}
} #while
return %valuesHash;
}

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# $Header: /cvsroot/pgsql/contrib/dbmirror/Attic/Makefile,v 1.1 2002/06/23 21:58:07 momjian Exp $
subdir = contrib/dbmirror
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
MODULES = pending
DOCS = README.dbmirror
include $(top_srcdir)/contrib/contrib-global.mk

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CREATE FUNCTION "recordchange" () RETURNS opaque AS
'/usr/local/pgsql/lib/pending.so', 'recordchange' LANGUAGE 'C';
CREATE TABLE "MirrorHost" (
"MirrorHostId" serial,
"HostName" varchar NOT NULL
);
CREATE TABLE "Pending" (
"SeqId" serial,
"TableName" varchar NOT NULL,
"Op" character,
"XID" int4 NOT NULL,
PRIMARY KEY ("SeqId")
);
CREATE INDEX "Pending_XID_Index" ON "Pending" ("XID");
CREATE TABLE "PendingData" (
"SeqId" int4 NOT NULL,
"IsKey" bool NOT NULL,
"Data" varchar,
PRIMARY KEY ("SeqId", "IsKey") ,
FOREIGN KEY ("SeqId") REFERENCES "Pending" ("SeqId") ON UPDATE CASCADE ON DELETE CASCADE
);
CREATE TABLE "MirroredTransaction" (
"XID" int4 NOT NULL,
"LastSeqId" int4 NOT NULL,
"MirrorHostId" int4 NOT NULL,
PRIMARY KEY ("XID","MirrorHostId"),
FOREIGN KEY ("MirrorHostId") REFERENCES "MirrorHost" ("MirrorHostId") ON UPDATE CASCADE ON DELETE CASCADE,
FOREIGN KEY ("LastSeqId") REFERENCES "Pending" ("SeqId") ON UPDATE
CASCADE ON DELETE CASCADE
);

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DBMirror - Postgres Database Mirroring
===================================================
DBMirror is a database mirroring system developed for the Postgres
database Written and maintened by Steven Singer(ssinger@navtechinc.com)
(c) 2001-2002 Navtech Systems Support Inc.
Released under the GNU Public License version 2. See COPYING.
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
GNU General Public License for more details.
Overrview
--------------------------------------------------------------------
The mirroring system is trigger based and provides the following key features:
-Support for multiple mirror slaves
-Transactions are maintained
-Per table selection of what gets mirrored.
The system is based on the idea that a master database exist where all
edits are made to the tables being mirrored. A trigger attatched to the
tables being mirrored runs logging information about the edit to
the Pending table and PendingData table.
A perl script(DBMirror.pl) runs continiously for each slave database(A database
that the change is supposed to be mirrored to) examining the Pending
table; searching for transactions that need to be sent to that particular slave
database. Those transactions are then mirrored to the slave database and
the MirroredTransaction table is updated to reflect that the transaction has
been sent.
If the transaction has been sent to all know slave hosts (All entries
in the MirrorHost table) then all records of it are purged from the
Pending tables.
Installation Instructions
------------------------------------------------------------------------
1) Compile pending.c
The file pending.c contains the recordchange trigger. This runs every
time a row inside of a table being mirrored changes.
To build the trigger run make on the "Makefile" in the DBMirror directory.
The Makefile supplied assumes that the postgres include files are in
/usr/local/pgsql/include/server.
Postgres-7.1.x installations should change this to
/usr/local/pgsql/include (The server part is for 7.2+)
If you have installed the postgres include files to another location then
modify the Makefile to reflect this.
The trigger requires that all postgres headers be installed, this is
accomplished in postgresql(7.1 or 7.2) by running "make install-all-headers"
in the postgres source directory.
The Makefile should create a file named pending.so that contains the trigger.
Install this file in /usr/local/pgsql/lib (or another suitable location).
If you choose a different location the MirrorSetup.sql script will need
to be modified to reflect your new location. The CREATE FUNCTION command
in the MirrorSetup.sql script associates the trigger function with the
pending.so shared library. Modify the arguments to this command if you
choose to install the trigger elsewhere.
2) Run MirroSetup.sql
This file contains SQL commands to setup the Mirroring environment.
This includes
-Telling Postgres about the "recordchange" trigger function.
-Creating the Pending,PendingData, MirrorHost, MirroredTransaction tables
To execute the script use psql as follows
"psql -f MirrorSetup.sql MyDatabaseName"
where MyDatabaseName is the name of the database you wish to install mirroring
on(Your master).
3) Create slaveDatabase.conf files.
Each slave database needs its own configuration file for the
DBMirror.pl script. See slaveDatabase.conf for a sample.
The master settings refer to the master database(The one that is
being mirrored).
The slave settings refer to the database that the data is being mirrored to.
The slaveHost parameter must refer to the machine name of the slave (Either
a resolvable hostname or an IP address). The value for slave host
must match the Hostname field in the MirrorHost table(See step 6).
The master user must have sufficient permissions to modify the Pending
tables and to read all of the tables being mirrored.
The slave user must have enough permissions on the slave database to
modify(INSERT,UPDATE,DELETE) any tables on the slave system that are being
mirrored.
4) Add the trigger to tables.
Execute the SQL code in AddTrigger.sql once for each table that should
be mirrored. Replace MyTableName with the name of the table that should
be mirrored.
5) Create the slave database.
The DBMirror system keeps the contents of mirrored tables identical on the
master and slave databases. When you first install the mirror triggers the
master and slave databases must be the same.
If you are starting with an empty master database then the slave should
be empty as well. Otherwise use pg_dump to ensure that the slave database
tables are initially identical to the master.
6) Add entries in the MirrorHost table.
Each slave database must have an entry in the MirrorHost table.
The name of the host in the MirrorHost table must exactly match the
slaveHost variable for that slave in the configuration file.
For example
INSERT INTO "MirrorHost" ("HostName") VALUES ('mySlaveMachine.mycompany.com');
6) Start DBMirror.pl
DBMirror.pl is the perl script that handles the mirroring.
It requires the Perl library Pg(See src/interfaces/perl5 in the postgres
source distribution).
It takes its configuration file as an argument(The one from step 3)
One instance of DBMirror.pl runs for each slave machine that is receiving
mirrored data.
Any errors are printed to standard out and emailed to the address specified in
the configuration file.
DBMirror can be run from the master, the slave, or a third machine as long
as it is able to access both the master and slave databases.
7) Periodically run clean_pending.pl
clean_pending.pl cleans out any entries from the Pending tables that
have already been mirrored to all hosts in the MirrorHost table.
It uses the same configuration file as DBMirror.pl.
Normally DBMirror.pl will clean these tables as it goes but in some
circumstances this will not happen.
For example if a transaction has been mirrored to all slaves except for
one, then that host is removed from the MirrorHost table(It stops being
a mirror slave) the transactions that had already been mirrored to
all the other hosts will not be deleted from the Pending tables by
DBMirror.pl since DBMirror.pl will run against these transactions again
since they have already been sent to all the other hosts.
clean_pending.pl will remove these transactions.
TODO(Current Limitations)
----------
-Support for selective mirroring based on the content of data.
-Support for BLOB's.
-Support for conflict resolution.
-Batching SQL commands in DBMirror for better performance over WAN's.
-Better support for dealing with Schema changes.
Tested Platforms:
------------------
DBMirror has been tested on the following configurations but should
work on any platform with Postgres >= 7.1 and Perl 5.6.
RedHat Linux 7.1 & 6.2
-Postgres 7.1.2
-Perl 5.6
Mandrake Linux 8.0(Limited Testing)
-Postgres 7.2
-Perl 5.6
Steven Singer
Navtech Systems Support Inc.
ssinger@navtechinc.com

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#!/usr/bin/perl
# clean_pending.pl
# This perl script removes entries from the pending,pendingKeys,
# pendingDeleteData tables that have already been mirrored to all hosts.
#
#
#
# Written by Steven Singer (ssinger@navtechinc.com)
# (c) 2001-2002 Navtech Systems Support Inc.
# Released under the GNU Public License version 2. See COPYING.
#
#
# 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
# GNU General Public License for more details.
#
##############################################################################
# $Id: clean_pending.pl,v 1.1 2002/06/23 21:58:08 momjian Exp $
##############################################################################
=head1 NAME
clean_pending.pl - A Perl script to remove old entries from the
pending, pendingKeys, and pendingDeleteData tables.
=head1 SYNPOSIS
clean_pending.pl databasename
=head1 DESCRIPTION
This Perl script connects to the database specified as a command line argument
on the local system. It uses a hard-coded username and password.
It then removes any entries from the pending, pendingDeleteData, and
pendingKeys tables that have already been sent to all hosts in mirrorHosts.
=cut
BEGIN {
# add in a global path to files
#Ensure that Pg is in the path.
}
use strict;
use Pg;
if ($#ARGV != 0) {
die "usage: clean_pending.pl configFile\n";
}
if( ! defined do $ARGV[0]) {
die("Invalid Configuration file $ARGV[0]");
}
#connect to the database.
my $connectString = "host=$::masterHost dbname=$::masterDb user=$::masterUser password=$::masterPassword";
my $dbConn = Pg::connectdb($connectString);
unless($dbConn->status == PGRES_CONNECTION_OK) {
printf("Can't connect to database\n");
die;
}
my $result = $dbConn->exec("BEGIN");
unless($result->resultStatus == PGRES_COMMAND_OK) {
die $dbConn->errorMessage;
}
#delete all transactions that have been sent to all mirrorhosts
#or delete everything if no mirror hosts are defined.
# Postgres takes the "SELECT COUNT(*) FROM "MirrorHost" and makes it into
# an InitPlan. EXPLAIN show's this.
my $deletePendingQuery = 'DELETE FROM "Pending" WHERE (SELECT ';
$deletePendingQuery .= ' COUNT(*) FROM "MirroredTransaction" WHERE ';
$deletePendingQuery .= ' "XID"="Pending"."XID") = (SELECT COUNT(*) FROM ';
$deletePendingQuery .= ' "MirrorHost") OR (SELECT COUNT(*) FROM ';
$deletePendingQuery .= ' "MirrorHost") = 0';
my $result = $dbConn->exec($deletePendingQuery);
unless ($result->resultStatus == PGRES_COMMAND_OK ) {
printf($dbConn->errorMessage);
die;
}
$dbConn->exec("COMMIT");
$result = $dbConn->exec('VACUUM "Pending"');
unless ($result->resultStatus == PGRES_COMMAND_OK) {
printf($dbConn->errorMessage);
}
$result = $dbConn->exec('VACUUM "PendingData"');
unless($result->resultStatus == PGRES_COMMAND_OK) {
printf($dbConn->errorMessage);
}
$result = $dbConn->exec('VACUUM "MirroredTransaction"');
unless($result->resultStatus == PGRES_COMMAND_OK) {
printf($dbConn->errorMessage);
}

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/****************************************************************************
* pending.c
* $Id: pending.c,v 1.1 2002/06/23 21:58:08 momjian Exp $
*
* This file contains a trigger for Postgresql-7.x to record changes to tables
* to a pending table for mirroring.
* All tables that should be mirrored should have this trigger hooked up to it.
*
* Written by Steven Singer (ssinger@navtechinc.com)
* (c) 2001-2002 Navtech Systems Support Inc.
* Released under the GNU Public License version 2. See COPYING.
*
*
* 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
* GNU General Public License for more details.
*
*
***************************************************************************/
#include <executor/spi.h>
#include <commands/trigger.h>
#include <postgres.h>
enum FieldUsage {PRIMARY=0,NONPRIMARY,ALL,NUM_FIELDUSAGE};
int storePending(char * cpTableName, HeapTuple tBeforeTuple,
HeapTuple tAfterTuple,
TupleDesc tTupdesc,
TriggerData * tpTrigdata,char cOp);
int storeKeyInfo(char * cpTableName, HeapTuple tTupleData, TupleDesc tTuplDesc,
TriggerData * tpTrigdata);
int storeData(char * cpTableName,HeapTuple tTupleData,TupleDesc tTupleDesc,
TriggerData * tpTrigData,int iIncludeKeyData);
int2vector * getPrimaryKey(Oid tblOid);
char * packageData(HeapTuple tTupleData, TupleDesc tTupleDecs,
TriggerData * tTrigData,
enum FieldUsage eKeyUsage );
#define BUFFER_SIZE 256
#define MAX_OID_LEN 10
extern Datum recordchange(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(recordchange);
/*****************************************************************************
* The entry point for the trigger function.
* The Trigger takes a single SQL 'text' argument indicating the name of the
* table the trigger was applied to. If this name is incorrect so will the
* mirroring.
****************************************************************************/
Datum recordchange(PG_FUNCTION_ARGS) {
TriggerData * trigdata;
TupleDesc tupdesc;
HeapTuple beforeTuple=NULL;
HeapTuple afterTuple=NULL;
HeapTuple retTuple=NULL;
char * tblname;
char op;
if(fcinfo->context!=NULL) {
if(SPI_connect() < 0) {
elog(NOTICE,"storePending could not connect to SPI");
return -1;
}
trigdata = (TriggerData*)fcinfo->context;
/* Extract the table name */
tblname = SPI_getrelname(trigdata->tg_relation);
tupdesc = trigdata->tg_relation->rd_att;
if(TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event)) {
retTuple = trigdata->tg_newtuple;
beforeTuple = trigdata->tg_trigtuple;
afterTuple = trigdata->tg_newtuple;
op='u';
}
else if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event)) {
retTuple = trigdata->tg_trigtuple;
afterTuple = trigdata->tg_trigtuple;
op = 'i';
}
else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event)) {
retTuple = trigdata->tg_trigtuple;
beforeTuple = trigdata->tg_trigtuple;
op = 'd';
}
if(storePending(tblname,beforeTuple,afterTuple,tupdesc,trigdata,op)) {
/* An error occoured. Skip the operation. */
elog(ERROR,"Operation could not be mirrored");
return PointerGetDatum(NULL);
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"Returning on success");
#endif
SPI_finish();
return PointerGetDatum(retTuple);
}
else {
/*
* Not being called as a trigger.
*/
return PointerGetDatum(NULL);
}
}
/*****************************************************************************
* Constructs and executes an SQL query to write a record of this tuple change
* to the pending table.
*****************************************************************************/
int storePending(char * cpTableName, HeapTuple tBeforeTuple,
HeapTuple tAfterTuple,
TupleDesc tTupDesc,
TriggerData * tpTrigData,char cOp) {
char * cpQueryBase = "INSERT INTO \"Pending\" (\"TableName\",\"Op\",\"XID\") VALUES ($1,$2,$3)";
int iResult=0;
HeapTuple tCurTuple; // Points the current tuple(before or after)
Datum saPlanData[4];
Oid taPlanArgTypes[3] = {NAMEOID,CHAROID,INT4OID};
void * vpPlan;
tCurTuple = tBeforeTuple ? tBeforeTuple : tAfterTuple;
vpPlan = SPI_prepare(cpQueryBase,3,taPlanArgTypes);
if(vpPlan==NULL) {
elog(NOTICE,"Error creating plan");
}
// SPI_saveplan(vpPlan);
saPlanData[0] = PointerGetDatum(cpTableName);
saPlanData[1] = CharGetDatum(cOp);
saPlanData[2] = Int32GetDatum(GetCurrentTransactionId());
iResult = SPI_execp(vpPlan,saPlanData,NULL,1);
if(iResult < 0) {
elog(NOTICE,"storedPending fired (%s) returned %d",cpQueryBase,iResult);
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"row successfully stored in pending table");
#endif
if(cOp=='d') {
/**
* This is a record of a delete operation.
* Just store the key data.
*/
iResult = storeKeyInfo(cpTableName,tBeforeTuple,tTupDesc,tpTrigData);
}
else if (cOp=='i') {
/**
* An Insert operation.
* Store all data
*/
iResult = storeData(cpTableName,tAfterTuple,tTupDesc,tpTrigData,TRUE);
}
else {
/* op must be an update. */
iResult = storeKeyInfo(cpTableName,tBeforeTuple,tTupDesc,tpTrigData);
iResult = iResult ? iResult : storeData(cpTableName,tAfterTuple,tTupDesc,
tpTrigData,TRUE);
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"DOne storing keyinfo");
#endif
return iResult;
}
int storeKeyInfo(char * cpTableName, HeapTuple tTupleData,
TupleDesc tTupleDesc,
TriggerData * tpTrigData) {
Oid saPlanArgTypes[1] = {NAMEOID};
char * insQuery = "INSERT INTO \"PendingData\" (\"SeqId\",\"IsKey\",\"Data\") VALUES(currval('\"Pending_SeqId_seq\"'),'t',$1)";
void * pplan;
Datum saPlanData[1];
char * cpKeyData;
int iRetCode;
pplan = SPI_prepare(insQuery,1,saPlanArgTypes);
if(pplan==NULL) {
elog(NOTICE,"Could not prepare INSERT plan");
return -1;
}
// pplan = SPI_saveplan(pplan);
cpKeyData = packageData(tTupleData, tTupleDesc,tpTrigData,PRIMARY);
#if defined DEBUG_OUTPUT
elog(NOTICE,cpKeyData);
#endif
saPlanData[0] = PointerGetDatum(cpKeyData);
iRetCode = SPI_execp(pplan,saPlanData,NULL,1);
if(cpKeyData!=NULL) {
SPI_pfree(cpKeyData);
}
if(iRetCode != SPI_OK_INSERT ) {
elog(NOTICE,"Error inserting row in pendingDelete");
return -1;
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"INSERT SUCCESFULL");
#endif
return 0;
}
int2vector * getPrimaryKey(Oid tblOid) {
char * queryBase;
char * query;
bool isNull;
int2vector * resultKey;
int2vector * tpResultKey;
HeapTuple resTuple;
Datum resDatum;
int ret;
queryBase = "SELECT indkey FROM pg_index WHERE indisprimary='t' AND indrelid=";
query = SPI_palloc(strlen(queryBase) + MAX_OID_LEN+1);
sprintf(query,"%s%d",queryBase,tblOid);
ret = SPI_exec(query,1);
if(ret != SPI_OK_SELECT || SPI_processed != 1 ) {
elog(NOTICE,"Could not select primary index key");
return NULL;
}
resTuple = SPI_tuptable->vals[0];
resDatum = SPI_getbinval(resTuple,SPI_tuptable->tupdesc,1,&isNull);
tpResultKey = (int2vector*) DatumGetPointer(resDatum);
resultKey = SPI_palloc(sizeof(int2vector));
memcpy(resultKey,tpResultKey,sizeof(int2vector));
SPI_pfree(query);
return resultKey;
}
/******************************************************************************
* Stores a copy of the non-key data for the row.
*****************************************************************************/
int storeData(char * cpTableName,HeapTuple tTupleData,TupleDesc tTupleDesc,
TriggerData * tpTrigData,int iIncludeKeyData) {
Oid planArgTypes[1] = {NAMEOID};
char * insQuery = "INSERT INTO \"PendingData\" (\"SeqId\",\"IsKey\",\"Data\") VALUES(currval('\"Pending_SeqId_seq\"'),'f',$1)";
void * pplan;
Datum planData[1];
char * cpKeyData;
int iRetValue;
pplan = SPI_prepare(insQuery,1,planArgTypes);
if(pplan==NULL) {
elog(NOTICE,"Could not prepare INSERT plan");
return -1;
}
// pplan = SPI_saveplan(pplan);
if(iIncludeKeyData==0) {
cpKeyData = packageData(tTupleData, tTupleDesc,tpTrigData,NONPRIMARY);
}
else {
cpKeyData = packageData(tTupleData,tTupleDesc,tpTrigData,ALL);
}
planData[0] = PointerGetDatum(cpKeyData);
iRetValue = SPI_execp(pplan,planData,NULL,1);
if(cpKeyData!=0) {
SPI_pfree(cpKeyData);
}
if(iRetValue != SPI_OK_INSERT ) {
elog(NOTICE,"Error inserting row in pendingDelete");
return -1;
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"INSERT SUCCESFULL");
#endif
return 0;
}
/**
* Packages the data in tTupleData into a string of the format
* FieldName='value text' where any quotes inside of value text
* are escaped with a backslash and any backslashes in value text
* are esacped by a second back slash.
*
* tTupleDesc should be a description of the tuple stored in
* tTupleData.
*
* eFieldUsage specifies which fields to use.
* PRIMARY implies include only primary key fields.
* NONPRIMARY implies include only non-primary key fields.
* ALL implies include all fields.
*/
char * packageData(HeapTuple tTupleData, TupleDesc tTupleDesc,
TriggerData * tpTrigData,
enum FieldUsage eKeyUsage ) {
int iNumCols;
int2vector * tpPKeys=NULL;
int iColumnCounter;
char * cpDataBlock;
int iDataBlockSize;
int iUsedDataBlock;
iNumCols = tTupleDesc->natts;
if(eKeyUsage!=ALL) {
tpPKeys = getPrimaryKey(tpTrigData->tg_relation->rd_id);
if(tpPKeys==NULL) {
return NULL;
}
}
#if defined DEBUG_OUTPUT
if(tpPKeys!=NULL) {
elog(NOTICE,"Have primary keys");
}
#endif
cpDataBlock = SPI_palloc(BUFFER_SIZE);
iDataBlockSize = BUFFER_SIZE;
iUsedDataBlock = 0; /* To account for the null */
for(iColumnCounter=1; iColumnCounter <=iNumCols; iColumnCounter++) {
int iIsPrimaryKey;
int iPrimaryKeyIndex;
char * cpUnFormatedPtr;
char * cpFormatedPtr;
char * cpFieldName;
char * cpFieldData;
if(eKeyUsage!=ALL) {
//Determine if this is a primary key or not.
iIsPrimaryKey=0;
for(iPrimaryKeyIndex=0; (*tpPKeys)[iPrimaryKeyIndex]!=0;
iPrimaryKeyIndex++) {
if((*tpPKeys)[iPrimaryKeyIndex]==iColumnCounter) {
iIsPrimaryKey=1;
break;
}
}
if( iIsPrimaryKey ? (eKeyUsage!=PRIMARY) : (eKeyUsage!=NONPRIMARY)) {
/**
* Don't use.
*/
#if defined DEBUG_OUTPUT
elog(NOTICE,"Skipping column");
#endif
continue;
}
} /* KeyUsage!=ALL */
cpFieldName = DatumGetPointer(NameGetDatum(&tTupleDesc->attrs
[iColumnCounter-1]->attname));
#if defined DEBUG_OUTPUT
elog(NOTICE,cpFieldName);
#endif
while(iDataBlockSize - iUsedDataBlock < strlen(cpFieldName) +4) {
cpDataBlock = SPI_repalloc(cpDataBlock,iDataBlockSize + BUFFER_SIZE);
iDataBlockSize = iDataBlockSize + BUFFER_SIZE;
}
sprintf(cpDataBlock+iUsedDataBlock,"\"%s\"=",cpFieldName);
iUsedDataBlock = iUsedDataBlock + strlen(cpFieldName)+3;
cpFieldData=SPI_getvalue(tTupleData,tTupleDesc,iColumnCounter);
cpUnFormatedPtr = cpFieldData;
cpFormatedPtr = cpDataBlock + iUsedDataBlock;
if(cpFieldData!=NULL) {
*cpFormatedPtr='\'';
iUsedDataBlock++;
cpFormatedPtr++;
}
else {
*cpFormatedPtr=' ';
iUsedDataBlock++;
cpFormatedPtr++;
continue;
}
#if defined DEBUG_OUTPUT
elog(NOTICE,cpFieldData);
elog(NOTICE,"Starting format loop");
#endif
while(*cpUnFormatedPtr!=0) {
while(iDataBlockSize - iUsedDataBlock < 2) {
cpDataBlock = SPI_repalloc(cpDataBlock,iDataBlockSize+BUFFER_SIZE);
iDataBlockSize = iDataBlockSize + BUFFER_SIZE;
cpFormatedPtr = cpDataBlock + iUsedDataBlock;
}
if(*cpUnFormatedPtr=='\\' || *cpUnFormatedPtr=='\'') {
*cpFormatedPtr='\\';
cpFormatedPtr++;
iUsedDataBlock++;
}
*cpFormatedPtr=*cpUnFormatedPtr;
cpFormatedPtr++;
cpUnFormatedPtr++;
iUsedDataBlock++;
}
SPI_pfree(cpFieldData);
while(iDataBlockSize - iUsedDataBlock < 3) {
cpDataBlock = SPI_repalloc(cpDataBlock,iDataBlockSize+BUFFER_SIZE);
iDataBlockSize = iDataBlockSize + BUFFER_SIZE;
cpFormatedPtr = cpDataBlock + iUsedDataBlock;
}
sprintf(cpFormatedPtr,"' ");
iUsedDataBlock = iUsedDataBlock +2;
#if defined DEBUG_OUTPUT
elog(NOTICE,cpDataBlock);
#endif
} /* for iColumnCounter */
if(tpPKeys!=NULL) {
SPI_pfree(tpPKeys);
}
#if defined DEBUG_OUTPUT
elog(NOTICE,"Returning");
#endif
memset(cpDataBlock + iUsedDataBlock,0,iDataBlockSize - iUsedDataBlock);
return cpDataBlock;
}

22
contrib/dbmirror/slaveDatabase.conf Normal file
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@ -0,0 +1,22 @@
#########################################################################
# Config file for DBMirror.pl
# This file contains a sample configuration file for DBMirror.pl
# It contains configuration information to mirror data from
# the master database to a single slave system.
#
# $Id: slaveDatabase.conf,v 1.1 2002/06/23 21:58:08 momjian Exp $
#######################################################################
$masterHost = "masterMachine.mydomain.com";
$masterDb = "myDatabase";
$masterUser = "postgres";
$masterPassword = "postgrespassword";
# Where to email Error messages to
# $errorEmailAddr = "me@mydomain.com";
$slaveInfo->{"slaveHost"} = "backupMachine.mydomain.com";
$slaveInfo->{"slaveDb"} = "myDatabase";
$slaveInfo->{"slaveUser"} = "postgres";
$slaveInfo->{"slavePassword"} = "postgrespassword";