总结
想法1
自己运行代码的机器上不光需要下载官方的驱动，还要依赖数据库自身的动态库文件(意味着还要加载数据库自身的动态库)，感觉依赖太多，后来者有太多的包袱前行了，因为它需要从已有的数据库市场抢占份额，需要兼容的东西太多了，把自己弄成了四不像了，搞的开发者太累了，折腾的东西太多了，没有经历的开发者，几乎很难搞定，这是我的感受
想法2
就是因为有太多的兼容性，太复杂，它才有很多集成商们专门来做这个事，从方案设计到落地实施维护一体化的方案，你只管用，其它的事我包了
操作如下
建立项目目录结构(一定要先好自己最贴近的版本，我就吃了这个亏)
[root@vbox ~]# mkdir demoproject
[root@vbox ~]# wget https://opengauss.obs.cn-south-1.myhuaweicloud.com/6.0.1/openEuler22.03/x86/openGauss-Libpq-6.0.1-openEuler22.03-x86_64.tar.gz
[root@vbox ~]# mv openGauss-Libpq-6.0.1-openEuler22.03-x86_64.tar.gz demoproject/
[root@vbox ~]# cd demoproject/
[root@vbox demoproject]# tar -zxvf openGauss-Libpq-6.0.1-openEuler22.03-x86_64.tar.gz
[root@vbox demoproject]# ll
total 5404
drwxr-x---. 3 root root 4096 Jan 17 18:23 include
drwxr-x---. 2 root root 4096 Jan 17 18:23 lib
-rwxr-x---. 1 root root 5521498 Mar 21 08:37 openGauss-Libpq-6.0.1-openEuler22.03-x86_64.tar.gz
运行测试文件
[root@vbox demoproject]# gcc testlibpq.c -o test -I include -L lib -lpq
/usr/bin/ld: warning: libgssapi_krb5_gauss.so.2, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libgssrpc_gauss.so.4, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libkrb5_gauss.so.3, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libkrb5support_gauss.so.0, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libk5crypto_gauss.so.3, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libcom_err_gauss.so.3, needed by lib/libpq.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_display_status@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `GSS_KRB5_NT_PRINCIPAL_NAME@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `krb5_set_profile_path@krb5_gauss_3_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `krb5_clean_cache_profile_path@krb5_gauss_3_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_delete_sec_context@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_release_name@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_import_name@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_release_buffer@gssapi_krb5_gauss_2_MIT'
/usr/bin/ld: lib/libpq.so: undefined reference to `gss_init_sec_context@gssapi_krb5_gauss_2_MIT'
collect2: error: ld returned 1 exit status
[root@vbox demoproject]#
安装缺失包
挂载镜像
[root@vbox mnt]# mount -o loop openEuler-24.03-LTS-SP1-x86_64-dvd.iso /media/cdrom/
mount: media/cdrom: WARNING: source write-protected, mounted read-only.
[root@vbox mnt]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/openeuler-root ext4 17G 7.7G 8.1G 49% /
devtmpfs devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs tmpfs 729M 12K 729M 1% /dev/shm
tmpfs tmpfs 4.0M 0 4.0M 0% /sys/fs/cgroup
tmpfs tmpfs 292M 4.3M 288M 2% /run
tmpfs tmpfs 729M 8.0K 729M 1% /tmp
/dev/sda2 ext4 974M 210M 697M 24% /boot
D_DRIVE vboxsf 257G 101G 156G 40% /mnt
/dev/loop0 iso9660 4.1G 4.1G 0 100% /media/cdrom
[root@vbox mnt]#
为镜像设置YUM源
cd /etc/yum.repos.d/
mv openEuler.repo openEuler.repo.bak
vi openEuler.repo
下载密钥
[root@vbox demoproject]# wget http://repo.openeuler.org/openEuler-24.03-LTS-SP1/OS/x86_64/RPM-GPG-KEY-openEuler
配置镜像
[cdrom]
baseurl=file:///media/cdrom
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-openEuler
运行
[root@vbox demoproject]# ll
total 5428
drwxr-x---. 3 root root 4096 Jan 17 18:23 include
drwxr-x---. 2 root root 4096 Jan 17 18:23 lib
-rwxr-x---. 1 root root 5521498 Mar 21 08:37 openGauss-Libpq-6.0.1-openEuler22.03-x86_64.tar.gz
-rwxr-xr-x. 1 root root 16976 Mar 21 09:27 test
-rw-r--r--. 1 root root 2768 Mar 21 08:39 testlibpq.c
[root@vbox demoproject]#
[root@vbox demoproject]# sudo find / -name "libgssapi_krb5_gauss.so.2"
/usr/local/opengauss/lib/libgssapi_krb5_gauss.so.2
[root@vbox demoproject]# export LD_LIBRARY_PATH=/usr/local/opengauss/lib:$LD_LIBRARY_PATH
[root@vbox demoproject]# echo $LD_LIBRARY_PATH
/usr/local/opengauss/lib:://var/lib/opengauss/c/lib:/var/lib/opengauss/c/demoproject/lib
[root@vbox demoproject]# gcc testlibpq.c -o test -I include -L lib -lpq
建立数据库权限
[opengauss@vbox ~]$ gsql -p7654 -r
openGauss=# create user test password 'test_1234';
CREATE ROLE
openGauss=# \q
[opengauss@vbox ~]$ gsql -p7654 -U test -W 'test_1234' -h 127.0.0.1
gsql ((openGauss 6.0.0 build ) compiled at 2024-12-19 00:17:38 commit 0 last mr release)
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
openGauss=>
运行代码
[root@vbox demoproject]# vim testlibpq.c
[root@vbox demoproject]# gcc testlibpq.c -o test -I include -L lib -lpq
[root@vbox demoproject]# ./test
datname datdba encoding datcollate datctype datistemplate datallowconn datconnlimit datlastsysoid datfrozenxid dattablespace datcompatibilitydatacl datfrozenxid64 datminmxid
template1 10 7 en_US.UTF-8 en_US.UTF-8 t t -1 14893 0 1663 A {=c/opengauss,opengauss=CTc/opengauss}11565 2
hu 10 7 en_US.UTF-8 en_US.UTF-8 f t -1 14893 11210 1663 A 11210 2
template0 10 7 en_US.UTF-8 en_US.UTF-8 t f -1 14893 0 1663 A {=c/opengauss,opengauss=CTc/opengauss}11210 2
postgres 10 7 en_US.UTF-8 en_US.UTF-8 f t -1 14893 0 1663 A 11920 2
[root@vbox demoproject]#
测试代码
/*
* testlibpq.c
*/
#include <stdio.h>
#include <stdlib.h>
#include <libpq-fe.h>
static void
exit_nicely(PGconn *conn)
{
PQfinish(conn);
exit(1);
}
int
main(int argc, char **argv)
{
const char *conninfo;
PGconn *conn;
PGresult *res;
int nFields;
int i,j;
/*
* 用户在命令行上提供了conninfo字符串的值时使用该值
* 否则环境变量或者所有其它连接参数
* 都使用缺省值。
*/
if (argc > 1)
conninfo = argv[1];
else
conninfo = "dbname=postgres port=42121 host='10.44.133.171' application_name=test connect_timeout=5 sslmode=allow user='test' password='test_1234'";
/* 连接数据库 */
conn = PQconnectdb(conninfo);
/* 检查后端连接成功建立 */
if (PQstatus(conn) != CONNECTION_OK)
{
fprintf(stderr, "Connection to database failed: %s",
PQerrorMessage(conn));
exit_nicely(conn);
}
/*
* 测试实例涉及游标的使用时候必须使用事务块
*把全部放在一个 "select * from pg_database"
* PQexec() 里，过于简单，不推荐使用
*/
/* 开始一个事务块 */
res = PQexec(conn, "BEGIN");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "BEGIN command failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
/*
* 在结果不需要的时候PQclear PGresult，以避免内存泄漏
*/
PQclear(res);
/*
* 从系统表 pg_database（数据库的系统目录）里抓取数据
*/
res = PQexec(conn, "DECLARE myportal CURSOR FOR select * from pg_database");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "DECLARE CURSOR failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
PQclear(res);
res = PQexec(conn, "FETCH ALL in myportal");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, "FETCH ALL failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
/* 打印属性名称 */
nFields = PQnfields(res);
for (i = 0; i < nFields; i++)
printf("%-15s", PQfname(res, i));
printf("\n\n");
/* 打印行 */
for (i = 0; i < PQntuples(res); i++)
{
for (j = 0; j < nFields; j++)
printf("%-15s", PQgetvalue(res, i, j));
printf("\n");
}
PQclear(res);
/* 关闭入口 ... 不用检查错误 ... */
res = PQexec(conn, "CLOSE myportal");
PQclear(res);
/* 结束事务 */
res = PQexec(conn, "END");
PQclear(res);
/* 关闭数据库连接并清理 */
PQfinish(conn);
return 0;
}
参考
示例 Libpq | openGauss文档 | openGauss社区
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