crosstabview.h File Reference

#include "libpq-fe.h"

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Macros
#define	CROSSTABVIEW_MAX_COLUMNS   1600

Functions
bool	PrintResultInCrosstab (const PGresult *res)

Macro Definition Documentation

CROSSTABVIEW_MAX_COLUMNS

#define CROSSTABVIEW_MAX_COLUMNS   1600

Definition at line 24 of file crosstabview.h.

Function Documentation

PrintResultInCrosstab()

bool PrintResultInCrosstab

(

const PGresult *

res

)

Definition at line 104 of file crosstabview.c.

{
    bool        retval = false;
    avl_tree    piv_columns;
    avl_tree    piv_rows;
    pivot_field *array_columns = NULL;
    pivot_field *array_rows = NULL;
    int         num_columns = 0;
    int         num_rows = 0;
    int         field_for_rows;
    int         field_for_columns;
    int         field_for_data;
    int         sort_field_for_columns;
    int         rn;
 
    avlInit(&piv_rows);
    avlInit(&piv_columns);
 
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        pg_log_error("\\crosstabview: statement did not return a result set");
        goto error_return;
    }
 
    if (PQnfields(res) < 3)
    {
        pg_log_error("\\crosstabview: query must return at least three columns");
        goto error_return;
    }
 
    /* Process first optional arg (vertical header column) */
    if (pset.ctv_args[0] == NULL)
        field_for_rows = 0;
    else
    {
        field_for_rows = indexOfColumn(pset.ctv_args[0], res);
        if (field_for_rows < 0)
            goto error_return;
    }
 
    /* Process second optional arg (horizontal header column) */
    if (pset.ctv_args[1] == NULL)
        field_for_columns = 1;
    else
    {
        field_for_columns = indexOfColumn(pset.ctv_args[1], res);
        if (field_for_columns < 0)
            goto error_return;
    }
 
    /* Insist that header columns be distinct */
    if (field_for_columns == field_for_rows)
    {
        pg_log_error("\\crosstabview: vertical and horizontal headers must be different columns");
        goto error_return;
    }
 
    /* Process third optional arg (data column) */
    if (pset.ctv_args[2] == NULL)
    {
        int         i;
 
        /*
         * If the data column was not specified, we search for the one not
         * used as either vertical or horizontal headers.  Must be exactly
         * three columns, or this won't be unique.
         */
        if (PQnfields(res) != 3)
        {
            pg_log_error("\\crosstabview: data column must be specified when query returns more than three columns");
            goto error_return;
        }
 
        field_for_data = -1;
        for (i = 0; i < PQnfields(res); i++)
        {
            if (i != field_for_rows && i != field_for_columns)
            {
                field_for_data = i;
                break;
            }
        }
        Assert(field_for_data >= 0);
    }
    else
    {
        field_for_data = indexOfColumn(pset.ctv_args[2], res);
        if (field_for_data < 0)
            goto error_return;
    }
 
    /* Process fourth optional arg (horizontal header sort column) */
    if (pset.ctv_args[3] == NULL)
        sort_field_for_columns = -1;    /* no sort column */
    else
    {
        sort_field_for_columns = indexOfColumn(pset.ctv_args[3], res);
        if (sort_field_for_columns < 0)
            goto error_return;
    }
 
    /*
     * First part: accumulate the names that go into the vertical and
     * horizontal headers, each into an AVL binary tree to build the set of
     * DISTINCT values.
     */
 
    for (rn = 0; rn < PQntuples(res); rn++)
    {
        char       *val;
        char       *val1;
 
        /* horizontal */
        val = PQgetisnull(res, rn, field_for_columns) ? NULL :
            PQgetvalue(res, rn, field_for_columns);
        val1 = NULL;
 
        if (sort_field_for_columns >= 0 &&
            !PQgetisnull(res, rn, sort_field_for_columns))
            val1 = PQgetvalue(res, rn, sort_field_for_columns);
 
        avlMergeValue(&piv_columns, val, val1);
 
        if (piv_columns.count > CROSSTABVIEW_MAX_COLUMNS)
        {
            pg_log_error("\\crosstabview: maximum number of columns (%d) exceeded",
                         CROSSTABVIEW_MAX_COLUMNS);
            goto error_return;
        }
 
        /* vertical */
        val = PQgetisnull(res, rn, field_for_rows) ? NULL :
            PQgetvalue(res, rn, field_for_rows);
 
        avlMergeValue(&piv_rows, val, NULL);
    }
 
    /*
     * Second part: Generate sorted arrays from the AVL trees.
     */
 
    num_columns = piv_columns.count;
    num_rows = piv_rows.count;
 
    array_columns = (pivot_field *)
        pg_malloc(sizeof(pivot_field) * num_columns);
 
    array_rows = (pivot_field *)
        pg_malloc(sizeof(pivot_field) * num_rows);
 
    avlCollectFields(&piv_columns, piv_columns.root, array_columns, 0);
    avlCollectFields(&piv_rows, piv_rows.root, array_rows, 0);
 
    /*
     * Third part: optionally, process the ranking data for the horizontal
     * header
     */
    if (sort_field_for_columns >= 0)
        rankSort(num_columns, array_columns);
 
    /*
     * Fourth part: print the crosstab'ed result.
     */
    retval = printCrosstab(res,
                           num_columns, array_columns, field_for_columns,
                           num_rows, array_rows, field_for_rows,
                           field_for_data);
 
error_return:
    avlFree(&piv_columns, piv_columns.root);
    avlFree(&piv_rows, piv_rows.root);
    pg_free(array_columns);
    pg_free(array_rows);
 
    return retval;
}

References Assert(), avlCollectFields(), avlFree(), avlInit(), avlMergeValue(), _avl_tree::count, CROSSTABVIEW_MAX_COLUMNS, _psqlSettings::ctv_args, i, indexOfColumn(), pg_free(), pg_log_error, pg_malloc(), PGRES_TUPLES_OK, PQgetisnull(), PQgetvalue(), PQnfields(), PQntuples(), PQresultStatus(), printCrosstab(), pset, rankSort(), _avl_tree::root, and val.

Referenced by PrintQueryResult().