Bruce Momjian
parent
b33c66234e
commit
5af4855383
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@ -38,6 +38,10 @@ dbase -
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Converts from dbase/xbase to PostgreSQL
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by Ivan Baldo, lubaldo@adinet.com.uy
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dblink -
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Allows remote query execution
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by Joe Conway, joe.conway@mail.com
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earthdistance -
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Operator for computing earth distance for two points
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by Hal Snyder <hal@vailsys.com>
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@ -0,0 +1,48 @@
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subdir = contrib/dblink
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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include $(top_builddir)/src/Makefile.shlib
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include_srcdir = $(top_builddir)/src/include
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NAME := dblink
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SONAME := $(NAME)$(DLSUFFIX)
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override CFLAGS += -I$(srcdir)
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override CFLAGS += -I$(include_srcdir)
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override CFLAGS += -I$(libpq_srcdir)
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override CFLAGS += $(CFLAGS_SL)
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OBJS = $(NAME).o
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all: $(OBJS) $(SONAME) $(NAME).sql
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$(OBJS): $(NAME).c
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$(CC) -o $@ -c $(CFLAGS) $<
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$(SONAME): $(OBJS)
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$(LD) -o $@ -Bshareable $(libpq) $<
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$(NAME).sql: $(NAME).sql.in
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sed -e 's:MODULE_PATHNAME:$(libdir)/contrib/$(SONAME):g' < $< > $@
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install: all installdirs
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$(INSTALL_DATA) README.$(NAME) $(docdir)/contrib
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$(INSTALL_DATA) $(NAME).sql $(datadir)/contrib
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$(INSTALL_SHLIB) $(SONAME) $(libdir)/contrib
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installdirs:
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$(mkinstalldirs) $(docdir)/contrib $(datadir)/contrib $(libdir)/contrib
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uninstall:
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rm -rf $(docdir)/contrib/README.$(NAME) $(datadir)/contrib/$(NAME).sql $(libdir)/contrib/$(SONAME)
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clean distclean maintainer-clean:
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rm -f $(SONAME) *.o *.sql
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depend dep:
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$(CC) -MM -MG $(CFLAGS) *.c > depend
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ifeq (depend,$(wildcard depend))
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include depend
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endif
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@ -0,0 +1,157 @@
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/*
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* dblink
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*
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* Functions returning results from a remote database
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*
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* Copyright (c) Joseph Conway <joe.conway@mail.com>, 2001;
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose, without fee, and without a written agreement
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* is hereby granted, provided that the above copyright notice and this
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* paragraph and the following two paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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*/
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Version 0.2 (29 May, 2001):
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Function to test returning data set from remote database
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Tested under Linux (Red Hat 6.2 and 7.0) and PostgreSQL 7.1 and 7.2devel
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Release Notes:
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Version 0.2
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- initial release
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Installation:
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Place these files in a directory called 'dblink' under 'contrib' in the PostgreSQL source tree. Then run:
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make
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make install
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You can use dblink.sql to create the functions in your database of choice, e.g.
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psql -U postgres template1 < dblink.sql
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installs following functions into database template1:
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dblink() - returns a pointer to results from remote query
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dblink_tok() - extracts and returns individual field results
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Documentation
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==================================================================
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Name
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dblink -- Returns a pointer to a data set from a remote database
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Synopsis
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dblink(text connstr, text sql)
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Inputs
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connstr
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standard libpq format connection srting,
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e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
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sql
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sql statement that you wish to execute on the remote host
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e.g. "select * from pg_class"
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Outputs
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Returns setof int (pointer)
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Example usage
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select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd','select f1, f2 from mytable');
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==================================================================
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Name
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dblink_tok -- Returns individual select field results from a dblink remote query
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Synopsis
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dblink_tok(int pointer, int fnumber)
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Inputs
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pointer
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a pointer returned by a call to dblink()
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fnumber
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the ordinal position (zero based) of the field to be returned from the dblink result set
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Outputs
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Returns text
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Example usage
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select dblink_tok(t1.dblink_p,0) as f1, dblink_tok(t1.dblink_p,1) as f2
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from (select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
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,'select f1, f2 from mytable') as dblink_p) as t1;
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==================================================================
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NOTE: If you need to provide selection criteria in a WHERE clause, it is necessary
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to 'fake' a UNION, e.g.
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select
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dblink_tok(t1.dblink_p,0) as f1
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,dblink_tok(t1.dblink_p,1) as f2
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from
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(
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select dblink(
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'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
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,'select f1, f2 from mytable'
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) as dblink_p
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union
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select null,null where false
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) as t1
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where
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f1 = 'mycriteria';
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in order to work around an issue with the query optimizer. A more convenient way to approach
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this problem is to create a view:
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create view myremotetable as
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select
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dblink_tok(t1.dblink_p,0) as f1
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,dblink_tok(t1.dblink_p,1) as f2
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from
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(
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select dblink(
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'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
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,'select f1, f2 from mytable'
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) as dblink_p
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union
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select null,null where false
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) as t1;
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Then you can simply write:
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select f1,f2 from myremotetable where f1 = 'mycriteria';
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==================================================================
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-- Joe Conway
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@ -0,0 +1,276 @@
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/*
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* dblink.c
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*
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* Functions returning results from a remote database
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*
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* Copyright (c) Joseph Conway <joe.conway@mail.com>, 2001;
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose, without fee, and without a written agreement
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* is hereby granted, provided that the above copyright notice and this
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* paragraph and the following two paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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*/
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#include "dblink.h"
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PG_FUNCTION_INFO_V1(dblink);
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Datum
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dblink(PG_FUNCTION_ARGS)
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{
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PGconn *conn = NULL;
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PGresult *res = NULL;
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dblink_results *results;
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char *optstr;
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char *sqlstatement;
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char *curstr = "DECLARE mycursor CURSOR FOR ";
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char *execstatement;
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char *msg;
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int ntuples = 0;
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ReturnSetInfo *rsi;
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if (PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
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elog(ERROR, "dblink: NULL arguments are not permitted");
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}
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if (fcinfo->resultinfo == NULL || ! IsA(fcinfo->resultinfo, ReturnSetInfo)) {
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elog(ERROR, "dblink: function called in context that does not accept a set result");
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}
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optstr = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
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sqlstatement = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(1))));
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if (fcinfo->flinfo->fn_extra == NULL) {
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conn = PQconnectdb(optstr);
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if (PQstatus(conn) == CONNECTION_BAD)
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{
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msg = PQerrorMessage(conn);
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PQfinish(conn);
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elog(ERROR, "dblink: connection error: %s", msg);
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}
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res = PQexec(conn, "BEGIN");
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if (PQresultStatus(res) != PGRES_COMMAND_OK)
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{
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msg = PQerrorMessage(conn);
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PQclear(res);
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PQfinish(conn);
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elog(ERROR, "dblink: begin error: %s", msg);
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}
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PQclear(res);
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execstatement = (char *) palloc(strlen(curstr) + strlen(sqlstatement) + 1);
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if (execstatement != NULL) {
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strcpy(execstatement, curstr);
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strcat(execstatement, sqlstatement);
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strcat(execstatement, "\0");
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} else {
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elog(ERROR, "dblink: insufficient memory" );
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}
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res = PQexec(conn, execstatement);
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if (!res || (PQresultStatus(res) != PGRES_COMMAND_OK && PQresultStatus(res) != PGRES_TUPLES_OK))
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{
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msg = PQerrorMessage(conn);
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PQclear(res);
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PQfinish(conn);
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elog(ERROR, "dblink: sql error: %s", msg);
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} else {
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/*
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* got results, start fetching them
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*/
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PQclear(res);
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res = PQexec(conn, "FETCH ALL in mycursor");
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if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
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msg = PQerrorMessage(conn);
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PQclear(res);
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PQfinish(conn);
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elog(ERROR, "dblink: sql error: %s", msg);
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}
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ntuples = PQntuples(res);
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if (ntuples > 0) {
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results = init_dblink_results(fcinfo->flinfo->fn_mcxt);
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results->tup_num = 0;
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results->res = res;
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res = NULL;
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(dblink_results *) fcinfo->flinfo->fn_extra = results;
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results = NULL;
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results = fcinfo->flinfo->fn_extra;
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/* close the cursor */
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res = PQexec(conn, "CLOSE mycursor");
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PQclear(res);
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/* commit the transaction */
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res = PQexec(conn, "COMMIT");
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PQclear(res);
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/* close the connection to the database and cleanup */
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PQfinish(conn);
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rsi = (ReturnSetInfo *)fcinfo->resultinfo;
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rsi->isDone = ExprMultipleResult;
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PG_RETURN_POINTER(results);
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} else {
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PQclear(res);
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/* close the cursor */
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res = PQexec(conn, "CLOSE mycursor");
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PQclear(res);
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/* commit the transaction */
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res = PQexec(conn, "COMMIT");
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PQclear(res);
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/* close the connection to the database and cleanup */
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PQfinish(conn);
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rsi = (ReturnSetInfo *)fcinfo->resultinfo;
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rsi->isDone = ExprEndResult ;
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PG_RETURN_NULL();
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}
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}
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} else {
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/*
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* check for more results
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*/
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results = fcinfo->flinfo->fn_extra;
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results->tup_num++;
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ntuples = PQntuples(results->res);
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if (results->tup_num < ntuples) {
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/*
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* fetch them if available
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*/
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rsi = (ReturnSetInfo *)fcinfo->resultinfo;
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rsi->isDone = ExprMultipleResult;
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PG_RETURN_POINTER(results);
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} else {
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/*
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* or if no more, clean things up
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*/
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results = fcinfo->flinfo->fn_extra;
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PQclear(results->res);
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rsi = (ReturnSetInfo *)fcinfo->resultinfo;
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rsi->isDone = ExprEndResult ;
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PG_RETURN_NULL();
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}
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}
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PG_RETURN_NULL();
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}
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/*
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* dblink_tok
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* parse dblink output string
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* return fldnum item (0 based)
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* based on provided field separator
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*/
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PG_FUNCTION_INFO_V1(dblink_tok);
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Datum
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dblink_tok(PG_FUNCTION_ARGS)
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{
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dblink_results *results;
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int fldnum;
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text *result_text;
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char *result;
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int nfields = 0;
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int text_len = 0;
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if (PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
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elog(ERROR, "dblink: NULL arguments are not permitted");
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}
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results = (dblink_results *) PG_GETARG_POINTER(0);
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if (results == NULL) {
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elog(ERROR, "dblink: function called with invalid result pointer");
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}
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fldnum = PG_GETARG_INT32(1);
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if (fldnum < 0) {
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elog(ERROR, "dblink: field number < 0 not permitted");
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}
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nfields = PQnfields(results->res);
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if (fldnum > (nfields - 1)) {
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elog(ERROR, "dblink: field number %d does not exist", fldnum);
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}
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text_len = PQgetlength(results->res, results->tup_num, fldnum);
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result = (char *) palloc(text_len + 1);
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if (result != NULL) {
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strcpy(result, PQgetvalue(results->res, results->tup_num, fldnum));
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strcat(result, "\0");
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} else {
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elog(ERROR, "dblink: insufficient memory" );
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}
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result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(result)));
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PG_RETURN_TEXT_P(result_text);
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}
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/*
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* internal functions
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*/
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/*
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* init_dblink_results
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* - create an empty dblink_results data structure
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*/
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dblink_results *
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init_dblink_results(MemoryContext fn_mcxt)
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{
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MemoryContext oldcontext;
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dblink_results *retval;
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oldcontext = MemoryContextSwitchTo(fn_mcxt);
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retval = (dblink_results *) palloc(sizeof(dblink_results));
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MemSet(retval, 0, sizeof(dblink_results));
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retval->tup_num = -1;
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retval->res = NULL;
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MemoryContextSwitchTo(oldcontext);
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return retval;
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}
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|
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@ -0,0 +1,70 @@
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/*
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* dblink.h
|
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*
|
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* Functions returning results from a remote database
|
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*
|
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* Copyright (c) Joseph Conway <joe.conway@mail.com>, 2001;
|
||||
*
|
||||
* Permission to use, copy, modify, and distribute this software and its
|
||||
* documentation for any purpose, without fee, and without a written agreement
|
||||
* is hereby granted, provided that the above copyright notice and this
|
||||
* paragraph and the following two paragraphs appear in all copies.
|
||||
*
|
||||
* IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
|
||||
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
|
||||
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
|
||||
* DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
|
||||
* POSSIBILITY OF SUCH DAMAGE.
|
||||
*
|
||||
* THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
|
||||
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
|
||||
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
|
||||
* ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
|
||||
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
|
||||
*
|
||||
*/
|
||||
|
||||
#ifndef DBLINK_H
|
||||
#define DBLINK_H
|
||||
|
||||
#include <string.h>
|
||||
#include "postgres.h"
|
||||
#include "libpq-fe.h"
|
||||
#include "libpq-int.h"
|
||||
#include "fmgr.h"
|
||||
#include "access/tupdesc.h"
|
||||
#include "executor/executor.h"
|
||||
#include "nodes/nodes.h"
|
||||
#include "nodes/execnodes.h"
|
||||
#include "utils/builtins.h"
|
||||
|
||||
/*
|
||||
* This struct holds the results of the remote query.
|
||||
* Use fn_extra to hold a pointer to it across calls
|
||||
*/
|
||||
typedef struct
|
||||
{
|
||||
/*
|
||||
* last tuple number accessed
|
||||
*/
|
||||
int tup_num;
|
||||
|
||||
/*
|
||||
* the actual query results
|
||||
*/
|
||||
PGresult *res;
|
||||
|
||||
} dblink_results;
|
||||
|
||||
/*
|
||||
* External declarations
|
||||
*/
|
||||
extern Datum dblink(PG_FUNCTION_ARGS);
|
||||
extern Datum dblink_tok(PG_FUNCTION_ARGS);
|
||||
|
||||
/*
|
||||
* Internal declarations
|
||||
*/
|
||||
dblink_results *init_dblink_results(MemoryContext fn_mcxt);
|
||||
|
||||
#endif /* DBLINK_H */
|
||||
|
|
@ -0,0 +1,5 @@
|
|||
CREATE FUNCTION dblink (text,text) RETURNS setof int
|
||||
AS 'MODULE_PATHNAME','dblink' LANGUAGE 'c';
|
||||
|
||||
CREATE FUNCTION dblink_tok (int,int) RETURNS text
|
||||
AS 'MODULE_PATHNAME','dblink_tok' LANGUAGE 'c';
|
||||
Loading…
Reference in New Issue