lintel::postgresql::Cursor Class Reference

#include <Cursor.h>

Public Member Functions
	Cursor (const Connection &connection, const std::string &query, const std::vector< std::string > &params)
	Cursor (const Connection &connection, const std::string &query, const std::vector< std::string > &params, std::size_t fetchSize, const std::string &cursorName, bool noScroll)
	Cursor (Cursor &cursor)=delete
	~Cursor ()
std::vector< db::Arguments >	fetchNext (std::size_t maxRows)

Detailed Description

Forward-only cursor over a PostgreSQL query result.

Two modes:

• Streaming (fetchSize = 0): uses PQsetSingleRowMode so rows arrive one by one; the server executes the full query and the client buffers nothing. Good for moderate result sets.
• Server-side (fetchSize > 0): DECLARE CURSOR / FETCH / CLOSE. The server keeps state between FETCH calls, only transferring fetchSize rows per round-trip. Enables FOR UPDATE locking across multiple fetches.

The underlying Connection must outlive the cursor and must not run other queries while the cursor is active. The destructor closes (server-side) or drains (streaming) to leave the connection clean.

Constructor & Destructor Documentation

Cursor() [1/3]

lintel::postgresql::Cursor::Cursor ( const Connection &  connection, const std::string &  query, const std::vector< std::string > &  params  )

explicit

Streaming constructor (single-row mode, no DECLARE CURSOR).

Parameters

connection	the PostgreSQL connection (must outlive the cursor)
query	the SQL query with $1, $2, ... placeholders
params	the parameter values to bind

Exceptions

db::SQLException

if sending the query or switching to single-row mode fails

Cursor() [2/3]

lintel::postgresql::Cursor::Cursor ( const Connection &  connection, const std::string &  query, const std::vector< std::string > &  params, std::size_t  fetchSize, const std::string &  cursorName, bool  noScroll  )

explicit

Server-side cursor constructor (DECLARE CURSOR / FETCH / CLOSE).

Parameters

connection	the PostgreSQL connection (must outlive the cursor)
query	the SQL query with $1, $2, ... placeholders
params	the parameter values to bind
fetchSize	number of rows per FETCH (must be > 0)
cursorName	the cursor name; if empty a name is generated
noScroll	if true the cursor is declared NO SCROLL

Exceptions

db::SQLException

if DECLARE CURSOR fails

Cursor() [3/3]

lintel::postgresql::Cursor::Cursor ( Cursor &  cursor )

delete

~Cursor()

lintel::postgresql::Cursor::~Cursor

(

)

Destructor, closes or drains pending results.

Member Function Documentation

fetchNext()

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

(

std::size_t

maxRows

)

Fetches up to maxRows further rows from the query.

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

Exceptions

db::SQLException

on server-side failure

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

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