greenplumn crosstabview 源码
greenplumn crosstabview 代码
文件路径：/src/bin/psql/crosstabview.h
/*
* psql - the PostgreSQL interactive terminal
*
* Copyright (c) 2000-2019, PostgreSQL Global Development Group
*
* src/bin/psql/crosstabview.h
*/
#ifndef CROSSTABVIEW_H
#define CROSSTABVIEW_H
#include "libpq-fe.h"
/*
* Limit the number of output columns generated in memory by the crosstabview
* algorithm. A new output column is added for each distinct value found in the
* column that pivots (to form the horizontal header).
* The purpose of this limit is to fail early instead of over-allocating or spending
* too much time if the crosstab to generate happens to be unreasonably large
* (worst case: a NxN cartesian product with N=number of tuples).
* The value of 1600 corresponds to the maximum columns per table in storage,
* but it could be as much as INT_MAX theoretically.
*/
#define CROSSTABVIEW_MAX_COLUMNS 1600
/* prototypes */
extern bool PrintResultsInCrosstab(const PGresult *res);
#endif /* CROSSTABVIEW_H */
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