lintel::db::Cursor Class Reference

#include <Cursor.h>

Classes
class	Iterator

Public Member Functions
	Cursor ()=default
Cursor &	setFetchSize (std::size_t rows)
Cursor &	setCursorName (const std::string &name)
Cursor &	setNoScroll (bool enable)
std::vector< db::Arguments >	fetchNext (std::size_t maxRows)
Iterator	begin ()
Iterator	end ()

Friends
class	Statement

Detailed Description

Forward-only cursor over a query result.

Two modes controlled by fetchSize:

• fetchSize == 0: client-side streaming (PQsetSingleRowMode on PG).
• fetchSize > 0: server-side cursor (DECLARE/FETCH/CLOSE on PG, client-side prefetch buffer on SQLite). Default.

The cursor is single-pass: iterate it once with begin()/end(), or consume it with fetchNext(). The underlying Connection must outlive the cursor.

Configuration (setFetchSize / setCursorName / setNoScroll) must be called before the first call to begin() or fetchNext().

Constructor & Destructor Documentation

Cursor()

lintel::db::Cursor::Cursor ( )

default

Default constructor, creates an exhausted cursor.

Member Function Documentation

begin()

Iterator lintel::db::Cursor::begin

(

)

Starts the stream and returns an iterator to the first row.

end()

Iterator lintel::db::Cursor::end

(

)

Returns

iterator marking the end of the stream

fetchNext()

std::vector< db::Arguments > lintel::db::Cursor::fetchNext

(

std::size_t

maxRows

)

Fetches up to maxRows further rows from the stream.

Parameters

maxRows

maximum number of rows to fetch (must be > 0)

Returns

the fetched rows; fewer rows than requested means the result set is exhausted

setCursorName()

Cursor & lintel::db::Cursor::setCursorName

(

const std::string &

name

)

Sets the server-side cursor name. If empty (default), a unique name is auto-generated. Must be called before begin() or fetchNext().

setFetchSize()

Cursor & lintel::db::Cursor::setFetchSize

(

std::size_t

rows

)

Sets the number of rows fetched per backend round-trip. 0 = client-side streaming (PQsetSingleRowMode on PG, no DECLARE CURSOR) >0 = server-side cursor (DECLARE/FETCH/CLOSE on PG, prefetch buffer on SQLite) Default: 100 (server-side). Must be called before begin() or fetchNext().

setNoScroll()

Cursor & lintel::db::Cursor::setNoScroll

(

bool

enable

)

Sets the NO SCROLL flag on the server-side cursor. Default: true (NO SCROLL). Must be called before begin() or fetchNext().

Friends And Related Symbol Documentation

Statement

friend class Statement

friend

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The documentation for this class was generated from the following file:

• src/include/lintel/core/persistence/Cursor.h