---
title: "SPI_cursor_open"
id: spi-spi-cursor-open
pg_version: "20devel"
---

<a id="spi-spi-cursor-open"></a>

# SPI_cursor_open — set up a cursor using a statement created with `SPI_prepare`

## Synopsis

```
Portal SPI_cursor_open(const char * name, SPIPlanPtr plan,
                       const Datum * values, const char * nulls,
                       bool read_only)
```

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## Description

`SPI_cursor_open` sets up a cursor (internally, a portal) that will execute a statement prepared by `SPI_prepare`. The parameters have the same meanings as the corresponding parameters to `SPI_execute_plan`. 

Using a cursor instead of executing the statement directly has two benefits. First, the result rows can be retrieved a few at a time, avoiding memory overrun for queries that return many rows. Second, a portal can outlive the current C function (it can, in fact, live to the end of the current transaction). Returning the portal name to the C function's caller provides a way of returning a row set as result. 

The passed-in parameter data will be copied into the cursor's portal, so it can be freed while the cursor still exists. 

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## Arguments

**`const char * name`**

 name for portal, or `NULL` to let the system select a name **`SPIPlanPtr plan`**

 prepared statement (returned by `SPI_prepare`) **`Datum * values`**

 An array of actual parameter values. Must have same length as the statement's number of arguments. **`const char * nulls`**

 An array describing which parameters are null. Must have same length as the statement's number of arguments.  If `nulls` is `NULL` then `SPI_cursor_open` assumes that no parameters are null. Otherwise, each entry of the `nulls` array should be `' '` if the corresponding parameter value is non-null, or `'n'` if the corresponding parameter value is null. (In the latter case, the actual value in the corresponding `values` entry doesn't matter.) Note that `nulls` is not a text string, just an array: it does not need a `'\0'` terminator. **`bool read_only`**

`true` for read-only execution<a id="id-1.8.12.8.19.7"></a>

## Return Value

Pointer to portal containing the cursor. Note there is no error return convention; any error will be reported via `elog`.