对PostgreSQL的 SPI_prepare 的理解。

我找了很多的地方，都没有找到合适的例子。最后从PostgreSQL 的代码入手，找到一些例子，于是我做了一个小练习，还不错。

[作者：技术者高健@博客园  mail: luckyjackgao@gmail.com ]

#include "postgres.h"

#include "executor/spi.h"
#include "utils/builtins.h"
#include "catalog/pg_type.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

int plantest();

int plantest()
{

    char *command;
    int ret;
    int proc;


    SPI_connect();

    ////////////////////////////////////////////
    static SPIPlanPtr plan_getviewrule = NULL;
    static const char *query_getviewrule = 
    "SELECT * FROM pg_catalog.pg_rewrite WHERE ev_class = $1 AND rulename = $2";

        /*
         * On the first call prepare the plan to lookup pg_rewrite. We read
         * pg_rewrite over the SPI manager instead of using the syscache to be
         * checked for read access on pg_rewrite.
         */
        if (plan_getviewrule == NULL)
        {
                Oid                     argtypes[2];
                SPIPlanPtr      plan;

                argtypes[0] = OIDOID;
                argtypes[1] = NAMEOID;
                plan = SPI_prepare(query_getviewrule, 2, argtypes);
                if (plan == NULL)
                     elog(ERROR, 
                       "SPI_prepare failed for \"%s\"", query_getviewrule);
                SPI_keepplan(plan);
                plan_getviewrule = plan;
        }

    ////////////////////////////////////////////

    //ret = SPI_exec(command, cnt);

    //proc = SPI_processed;

    SPI_finish();
    pfree(command);

    return 0;
}

至少它可以运行。

[作者：技术者高健@博客园  mail: luckyjackgao@gmail.com ]