Converts from dbase/xbase to PostgreSQL
by Ivan Baldo, lubaldo@adinet.com.uy
+dblink -
+ Allows remote query execution
+ by Joe Conway, joe.conway@mail.com
+
earthdistance -
Operator for computing earth distance for two points
by Hal Snyder <hal@vailsys.com>
--- /dev/null
+subdir = contrib/dblink
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_builddir)/src/Makefile.shlib
+include_srcdir = $(top_builddir)/src/include
+
+
+NAME := dblink
+SONAME := $(NAME)$(DLSUFFIX)
+
+override CFLAGS += -I$(srcdir)
+override CFLAGS += -I$(include_srcdir)
+override CFLAGS += -I$(libpq_srcdir)
+override CFLAGS += $(CFLAGS_SL)
+
+OBJS = $(NAME).o
+
+all: $(OBJS) $(SONAME) $(NAME).sql
+
+$(OBJS): $(NAME).c
+ $(CC) -o $@ -c $(CFLAGS) $<
+
+$(SONAME): $(OBJS)
+ $(LD) -o $@ -Bshareable $(libpq) $<
+
+$(NAME).sql: $(NAME).sql.in
+ sed -e 's:MODULE_PATHNAME:$(libdir)/contrib/$(SONAME):g' < $< > $@
+
+install: all installdirs
+ $(INSTALL_DATA) README.$(NAME) $(docdir)/contrib
+ $(INSTALL_DATA) $(NAME).sql $(datadir)/contrib
+ $(INSTALL_SHLIB) $(SONAME) $(libdir)/contrib
+
+installdirs:
+ $(mkinstalldirs) $(docdir)/contrib $(datadir)/contrib $(libdir)/contrib
+
+uninstall:
+ rm -rf $(docdir)/contrib/README.$(NAME) $(datadir)/contrib/$(NAME).sql $(libdir)/contrib/$(SONAME)
+
+clean distclean maintainer-clean:
+ rm -f $(SONAME) *.o *.sql
+
+depend dep:
+ $(CC) -MM -MG $(CFLAGS) *.c > depend
+
+ifeq (depend,$(wildcard depend))
+include depend
+endif
--- /dev/null
+/*
+ * dblink
+ *
+ * Functions returning results from a remote database
+ *
+ * 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.
+ *
+ */
+
+Version 0.2 (29 May, 2001):
+ Function to test returning data set from remote database
+ Tested under Linux (Red Hat 6.2 and 7.0) and PostgreSQL 7.1 and 7.2devel
+
+Release Notes:
+
+ Version 0.2
+ - initial release
+
+Installation:
+ Place these files in a directory called 'dblink' under 'contrib' in the PostgreSQL source tree. Then run:
+
+ make
+ make install
+
+ You can use dblink.sql to create the functions in your database of choice, e.g.
+
+ psql -U postgres template1 < dblink.sql
+
+ installs following functions into database template1:
+
+ dblink() - returns a pointer to results from remote query
+ dblink_tok() - extracts and returns individual field results
+
+Documentation
+==================================================================
+Name
+
+dblink -- Returns a pointer to a data set from a remote database
+
+Synopsis
+
+dblink(text connstr, text sql)
+
+Inputs
+
+ connstr
+
+ standard libpq format connection srting,
+ e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
+
+ sql
+
+ sql statement that you wish to execute on the remote host
+ e.g. "select * from pg_class"
+
+Outputs
+
+ Returns setof int (pointer)
+
+Example usage
+
+ select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd','select f1, f2 from mytable');
+
+
+==================================================================
+
+Name
+
+dblink_tok -- Returns individual select field results from a dblink remote query
+
+Synopsis
+
+dblink_tok(int pointer, int fnumber)
+
+Inputs
+
+ pointer
+
+ a pointer returned by a call to dblink()
+
+ fnumber
+
+ the ordinal position (zero based) of the field to be returned from the dblink result set
+
+Outputs
+
+ Returns text
+
+Example usage
+
+ select dblink_tok(t1.dblink_p,0) as f1, dblink_tok(t1.dblink_p,1) as f2
+ from (select dblink('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+ ,'select f1, f2 from mytable') as dblink_p) as t1;
+
+
+==================================================================
+
+NOTE: If you need to provide selection criteria in a WHERE clause, it is necessary
+to 'fake' a UNION, e.g.
+
+ select
+ dblink_tok(t1.dblink_p,0) as f1
+ ,dblink_tok(t1.dblink_p,1) as f2
+ from
+ (
+ select dblink(
+ 'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+ ,'select f1, f2 from mytable'
+ ) as dblink_p
+ union
+ select null,null where false
+ ) as t1
+ where
+ f1 = 'mycriteria';
+
+in order to work around an issue with the query optimizer. A more convenient way to approach
+this problem is to create a view:
+
+ create view myremotetable as
+ select
+ dblink_tok(t1.dblink_p,0) as f1
+ ,dblink_tok(t1.dblink_p,1) as f2
+ from
+ (
+ select dblink(
+ 'hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd'
+ ,'select f1, f2 from mytable'
+ ) as dblink_p
+ union
+ select null,null where false
+ ) as t1;
+
+Then you can simply write:
+
+ select f1,f2 from myremotetable where f1 = 'mycriteria';
+
+==================================================================
+
+-- Joe Conway
+
--- /dev/null
+/*
+ * dblink.c
+ *
+ * Functions returning results from a remote database
+ *
+ * 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.
+ *
+ */
+
+#include "dblink.h"
+
+PG_FUNCTION_INFO_V1(dblink);
+Datum
+dblink(PG_FUNCTION_ARGS)
+{
+ PGconn *conn = NULL;
+ PGresult *res = NULL;
+ dblink_results *results;
+ char *optstr;
+ char *sqlstatement;
+ char *curstr = "DECLARE mycursor CURSOR FOR ";
+ char *execstatement;
+ char *msg;
+ int ntuples = 0;
+ ReturnSetInfo *rsi;
+
+ if (PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
+ elog(ERROR, "dblink: NULL arguments are not permitted");
+ }
+
+ if (fcinfo->resultinfo == NULL || ! IsA(fcinfo->resultinfo, ReturnSetInfo)) {
+ elog(ERROR, "dblink: function called in context that does not accept a set result");
+ }
+
+ optstr = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
+ sqlstatement = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(1))));
+
+ if (fcinfo->flinfo->fn_extra == NULL) {
+
+ conn = PQconnectdb(optstr);
+ if (PQstatus(conn) == CONNECTION_BAD)
+ {
+ msg = PQerrorMessage(conn);
+ PQfinish(conn);
+ elog(ERROR, "dblink: connection error: %s", msg);
+ }
+
+ res = PQexec(conn, "BEGIN");
+ if (PQresultStatus(res) != PGRES_COMMAND_OK)
+ {
+ msg = PQerrorMessage(conn);
+ PQclear(res);
+ PQfinish(conn);
+ elog(ERROR, "dblink: begin error: %s", msg);
+ }
+ PQclear(res);
+
+ execstatement = (char *) palloc(strlen(curstr) + strlen(sqlstatement) + 1);
+ if (execstatement != NULL) {
+ strcpy(execstatement, curstr);
+ strcat(execstatement, sqlstatement);
+ strcat(execstatement, "\0");
+ } else {
+ elog(ERROR, "dblink: insufficient memory" );
+ }
+
+ res = PQexec(conn, execstatement);
+ if (!res || (PQresultStatus(res) != PGRES_COMMAND_OK && PQresultStatus(res) != PGRES_TUPLES_OK))
+ {
+ msg = PQerrorMessage(conn);
+ PQclear(res);
+ PQfinish(conn);
+ elog(ERROR, "dblink: sql error: %s", msg);
+ } else {
+ /*
+ * got results, start fetching them
+ */
+ PQclear(res);
+
+ res = PQexec(conn, "FETCH ALL in mycursor");
+ if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
+ msg = PQerrorMessage(conn);
+ PQclear(res);
+ PQfinish(conn);
+ elog(ERROR, "dblink: sql error: %s", msg);
+ }
+
+ ntuples = PQntuples(res);
+
+ if (ntuples > 0) {
+
+ results = init_dblink_results(fcinfo->flinfo->fn_mcxt);
+ results->tup_num = 0;
+ results->res = res;
+ res = NULL;
+
+ (dblink_results *) fcinfo->flinfo->fn_extra = results;
+
+ results = NULL;
+ results = fcinfo->flinfo->fn_extra;
+
+ /* close the cursor */
+ res = PQexec(conn, "CLOSE mycursor");
+ PQclear(res);
+
+ /* commit the transaction */
+ res = PQexec(conn, "COMMIT");
+ PQclear(res);
+
+ /* close the connection to the database and cleanup */
+ PQfinish(conn);
+
+ rsi = (ReturnSetInfo *)fcinfo->resultinfo;
+ rsi->isDone = ExprMultipleResult;
+
+ PG_RETURN_POINTER(results);
+
+ } else {
+
+ PQclear(res);
+
+ /* close the cursor */
+ res = PQexec(conn, "CLOSE mycursor");
+ PQclear(res);
+
+ /* commit the transaction */
+ res = PQexec(conn, "COMMIT");
+ PQclear(res);
+
+ /* close the connection to the database and cleanup */
+ PQfinish(conn);
+
+ rsi = (ReturnSetInfo *)fcinfo->resultinfo;
+ rsi->isDone = ExprEndResult ;
+
+ PG_RETURN_NULL();
+ }
+ }
+ } else {
+ /*
+ * check for more results
+ */
+
+ results = fcinfo->flinfo->fn_extra;
+ results->tup_num++;
+ ntuples = PQntuples(results->res);
+
+ if (results->tup_num < ntuples) {
+
+ /*
+ * fetch them if available
+ */
+
+ rsi = (ReturnSetInfo *)fcinfo->resultinfo;
+ rsi->isDone = ExprMultipleResult;
+
+ PG_RETURN_POINTER(results);
+
+ } else {
+
+ /*
+ * or if no more, clean things up
+ */
+
+ results = fcinfo->flinfo->fn_extra;
+
+ PQclear(results->res);
+
+ rsi = (ReturnSetInfo *)fcinfo->resultinfo;
+ rsi->isDone = ExprEndResult ;
+
+ PG_RETURN_NULL();
+ }
+ }
+ PG_RETURN_NULL();
+}
+
+
+/*
+ * dblink_tok
+ * parse dblink output string
+ * return fldnum item (0 based)
+ * based on provided field separator
+ */
+
+PG_FUNCTION_INFO_V1(dblink_tok);
+Datum
+dblink_tok(PG_FUNCTION_ARGS)
+{
+ dblink_results *results;
+ int fldnum;
+ text *result_text;
+ char *result;
+ int nfields = 0;
+ int text_len = 0;
+
+ if (PG_ARGISNULL(0) || PG_ARGISNULL(1)) {
+ elog(ERROR, "dblink: NULL arguments are not permitted");
+ }
+
+ results = (dblink_results *) PG_GETARG_POINTER(0);
+ if (results == NULL) {
+ elog(ERROR, "dblink: function called with invalid result pointer");
+ }
+
+ fldnum = PG_GETARG_INT32(1);
+ if (fldnum < 0) {
+ elog(ERROR, "dblink: field number < 0 not permitted");
+ }
+
+ nfields = PQnfields(results->res);
+ if (fldnum > (nfields - 1)) {
+ elog(ERROR, "dblink: field number %d does not exist", fldnum);
+ }
+
+ text_len = PQgetlength(results->res, results->tup_num, fldnum);
+
+ result = (char *) palloc(text_len + 1);
+
+ if (result != NULL) {
+ strcpy(result, PQgetvalue(results->res, results->tup_num, fldnum));
+ strcat(result, "\0");
+ } else {
+ elog(ERROR, "dblink: insufficient memory" );
+ }
+
+ result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(result)));
+
+ PG_RETURN_TEXT_P(result_text);
+}
+
+
+/*
+ * internal functions
+ */
+
+
+/*
+ * init_dblink_results
+ * - create an empty dblink_results data structure
+ */
+dblink_results *
+init_dblink_results(MemoryContext fn_mcxt)
+{
+ MemoryContext oldcontext;
+ dblink_results *retval;
+
+ oldcontext = MemoryContextSwitchTo(fn_mcxt);
+
+ retval = (dblink_results *) palloc(sizeof(dblink_results));
+ MemSet(retval, 0, sizeof(dblink_results));
+
+ retval->tup_num = -1;
+ retval->res = NULL;
+
+ MemoryContextSwitchTo(oldcontext);
+
+ return retval;
+}
--- /dev/null
+/*
+ * dblink.h
+ *
+ * Functions returning results from a remote database
+ *
+ * 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 */
--- /dev/null
+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';
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