-- Hoogle documentation, generated by Haddock -- See Hoogle, http://www.haskell.org/hoogle/ -- | low-level binding to libpq -- -- This is a binding to libpq: the C application programmer's interface -- to PostgreSQL. libpq is a set of library functions that allow client -- programs to pass queries to the PostgreSQL backend server and to -- receive the results of these queries. @package postgresql-libpq @version 0.8.2 -- | This is a binding to libpq: the C application programmer's interface -- to PostgreSQL. libpq is a set of library functions that allow client -- programs to pass queries to the PostgreSQL backend server and to -- receive the results of these queries. -- -- This is intended to be a very low-level interface to libpq. It -- provides memory management and a somewhat more consistent interface to -- error conditions. Application code should typically use a higher-level -- PostgreSQL binding. -- -- This interface is not safe, because libpq unfortunately conflates -- explicit disconnects with memory management. A use-after-free memory -- fault will result if a connection is used in any way after -- finish is called. This will likely cause a segfault, or return -- an error if memory has not yet been reused. Other more bizarre -- behaviors are possible, though unlikely by chance. Higher-level -- bindings need to be aware of this issue and need to ensure that -- application code cannot cause the functions in this module to be -- called on an finished connection. -- -- One possibility is to represent a connection in a higher-level -- interface as MVar (Maybe Connection), using Nothing -- to represent an explicitly disconnected state. This was done in an -- earlier incarnation of this library, however this was removed because -- a higher level binding is likely to use a similar construct to deal -- with other issues. Thus incorporating that in this module results in -- extra layers of indirection for relatively little functionality. module Database.PostgreSQL.LibPQ -- | Connection encapsulates a connection to the backend. data Connection -- | Makes a new connection to the database server. -- -- This function opens a new database connection using the parameters -- taken from the string conninfo. Its nonblocking analogues are -- connectStart and connectPoll. -- -- The passed string can be empty to use all default parameters, or it -- can contain one or more parameter settings separated by whitespace. -- Each parameter setting is in the form keyword = value. Spaces around -- the equal sign are optional. To write an empty value or a value -- containing spaces, surround it with single quotes, e.g., keyword = 'a -- value'. Single quotes and backslashes within the value must be escaped -- with a backslash, i.e., ' and \. connectdb :: ByteString -> IO Connection -- | Make a connection to the database server in a nonblocking manner. connectStart :: ByteString -> IO Connection -- | If connectStart succeeds, the next stage is to poll libpq so -- that it can proceed with the connection sequence. Use socket to -- obtain the Fd of the socket underlying the database connection. -- Loop thus: If connectPoll last returned PollingReading, -- wait until the socket is ready to read (as indicated by select(), -- poll(), or similar system function). Then call connectPoll -- again. Conversely, if connectPoll last returned -- PollingWriting, wait until the socket is ready to write, then -- call connectPoll again. If you have yet to call -- connectPoll, i.e., just after the call to connectStart, -- behave as if it last returned PollingWriting. Continue this -- loop until connectPoll returns PollingFailed, indicating -- the connection procedure has failed, or PollingOk, indicating -- the connection has been successfully made. connectPoll :: Connection -> IO PollingStatus -- | Allocate a Null Connection, which all libpq functions should safely -- fail on. newNullConnection :: IO Connection -- | Test if a connection is the Null Connection. isNullConnection :: Connection -> Bool -- | Resets the communication channel to the server. -- -- This function will close the connection to the server and attempt to -- reestablish a new connection to the same server, using all the same -- parameters previously used. This might be useful for error recovery if -- a working connection is lost. reset :: Connection -> IO () -- | Reset the communication channel to the server, in a nonblocking -- manner. resetStart :: Connection -> IO Bool -- | To initiate a connection reset, call resetStart. If it returns -- False, the reset has failed. If it returns True, poll -- the reset using resetPoll in exactly the same way as you would -- create the connection using connectPoll. resetPoll :: Connection -> IO PollingStatus data PollingStatus PollingFailed :: PollingStatus PollingReading :: PollingStatus PollingWriting :: PollingStatus PollingOk :: PollingStatus -- | Closes the connection to the server. -- -- Note that the Connection must not be used again after -- finish has been called. finish :: Connection -> IO () -- | Returns the database name of the connection. db :: Connection -> IO (Maybe ByteString) -- | Returns the user name of the connection. user :: Connection -> IO (Maybe ByteString) -- | Returns the password of the connection. pass :: Connection -> IO (Maybe ByteString) -- | Returns the server host name of the connection. host :: Connection -> IO (Maybe ByteString) -- | Returns the port of the connection. port :: Connection -> IO (Maybe ByteString) -- | Returns the command-line options passed in the connection request. options :: Connection -> IO (Maybe ByteString) data ConnStatus -- | The Connection is ready. ConnectionOk :: ConnStatus -- | The connection procedure has failed. ConnectionBad :: ConnStatus -- | Waiting for connection to be made. ConnectionStarted :: ConnStatus -- | Connection OK; waiting to send. ConnectionMade :: ConnStatus -- | Waiting for a response from the server. ConnectionAwaitingResponse :: ConnStatus -- | Received authentication; waiting for backend start-up to finish. ConnectionAuthOk :: ConnStatus -- | Negotiating environment-driven parameter settings. ConnectionSetEnv :: ConnStatus -- | Negotiating SSL encryption. ConnectionSSLStartup :: ConnStatus -- | Returns the status of the connection. -- -- The status can be one of a number of values. However, only two of -- these are seen outside of an asynchronous connection procedure: -- ConnectionOk and ConnectionBad. A good connection to the -- database has the status ConnectionOk. A failed connection -- attempt is signaled by status ConnectionBad. Ordinarily, an OK -- status will remain so until finish, but a communications -- failure might result in the status changing to ConnectionBad -- prematurely. In that case the application could try to recover by -- calling reset. -- -- See the entry for connectStart and connectPoll with -- regards to other status codes that might be seen. status :: Connection -> IO ConnStatus data TransactionStatus -- | currently idle TransIdle :: TransactionStatus -- | a command is in progress TransActive :: TransactionStatus -- | idle, in a valid transaction block TransInTrans :: TransactionStatus -- | idle, in a failed transaction block TransInError :: TransactionStatus -- | the connection is bad TransUnknown :: TransactionStatus -- | Returns the current in-transaction status of the server. -- -- TransActive is reported only when a query has been sent to the -- server and not yet completed. transactionStatus :: Connection -> IO TransactionStatus -- | Looks up a current parameter setting of the server. -- -- Certain parameter values are reported by the server automatically at -- connection startup or whenever their values change. -- parameterStatus can be used to interrogate these settings. It -- returns the current value of a parameter if known, or Nothing -- if the parameter is not known. parameterStatus :: Connection -> ByteString -> IO (Maybe ByteString) -- | Interrogates the frontend/backend protocol being used. -- -- Applications might wish to use this to determine whether certain -- features are supported. Currently, the possible values are 2 (2.0 -- protocol), 3 (3.0 protocol), or zero (connection bad). This will not -- change after connection startup is complete, but it could -- theoretically change during a connection reset. The 3.0 protocol will -- normally be used when communicating with PostgreSQL 7.4 or later -- servers; pre-7.4 servers support only protocol 2.0. (Protocol 1.0 is -- obsolete and not supported by libpq.) protocolVersion :: Connection -> IO Int -- | Returns an integer representing the backend version. -- -- Applications might use this to determine the version of the database -- server they are connected to. The number is formed by converting the -- major, minor, and revision numbers into two-decimal-digit numbers and -- appending them together. For example, version 8.1.5 will be returned -- as 80105, and version 8.2 will be returned as 80200 (leading zeroes -- are not shown). Zero is returned if the connection is bad. serverVersion :: Connection -> IO Int -- | Returns the error message most recently generated by an operation on -- the connection. -- -- Nearly all libpq functions will set a message for errorMessage -- if they fail. Note that by libpq convention, a nonempty -- errorMessage result can be multiple lines, and will include a -- trailing newline. The result string should not be expected to remain -- the same across operations on the Connection. errorMessage :: Connection -> IO (Maybe ByteString) -- | Obtains the file descriptor number of the connection socket to the -- server. (This will not change during normal operation, but could -- change during connection setup or reset.) socket :: Connection -> IO (Maybe Fd) -- | Returns the process CPid of the backend server process handling -- this connection. -- -- The backend PID is useful for debugging purposes and for comparison to -- NOTIFY messages (which include the PID of the notifying backend -- process). Note that the PID belongs to a process executing on the -- database server host, not the local host! backendPID :: Connection -> IO CPid -- | Returns True if the connection authentication method required a -- password, but none was available. Returns False if not. -- -- This function can be applied after a failed connection attempt to -- decide whether to prompt the user for a password. connectionNeedsPassword :: Connection -> IO Bool -- | Returns True if the connection authentication method used a -- password. Returns False if not. -- -- This function can be applied after either a failed or successful -- connection attempt to detect whether the server demanded a password. connectionUsedPassword :: Connection -> IO Bool -- | Result encapsulates the result of a query (or more precisely, -- of a single SQL command --- a query string given to sendQuery -- can contain multiple commands and thus return multiple instances of -- Result. data Result -- | Submits a command to the server and waits for the result. -- -- Returns a Result or possibly Nothing. A Result -- will generally be returned except in out-of-memory conditions or -- serious errors such as inability to send the command to the server. If -- a Nothing is returned, it should be treated like a -- FatalError result. Use errorMessage to get more -- information about such errors. -- -- It is allowed to include multiple SQL commands (separated by -- semicolons) in the command string. Multiple queries sent in a single -- exec call are processed in a single transaction, unless there -- are explicit BEGIN/COMMIT commands included in the query string to -- divide it into multiple transactions. Note however that the returned -- Result structure describes only the result of the last command -- executed from the string. Should one of the commands fail, processing -- of the string stops with it and the returned Result describes -- the error condition. exec :: Connection -> ByteString -> IO (Maybe Result) data Format Text :: Format Binary :: Format newtype Oid Oid :: CUInt -> Oid invalidOid :: Oid -- | Submits a command to the server and waits for the result, with the -- ability to pass parameters separately from the SQL command text. -- -- execParams is like exec, but offers additional -- functionality: parameter values can be specified separately from the -- command string proper, and query results can be requested in either -- text or binary format. execParams is supported only in protocol -- 3.0 and later connections; it will fail when using protocol 2.0. -- -- The primary advantage of execParams over exec is that -- parameter values can be separated from the command string, thus -- avoiding the need for tedious and error-prone quoting and escaping. -- -- Unlike exec, execParams allows at most one SQL command -- in the given string. (There can be semicolons in it, but not more than -- one nonempty command.) This is a limitation of the underlying -- protocol, but has some usefulness as an extra defense against -- SQL-injection attacks. -- -- Tip: Specifying parameter types via OIDs is tedious, particularly if -- you prefer not to hard-wire particular OID values into your program. -- However, you can avoid doing so even in cases where the server by -- itself cannot determine the type of the parameter, or chooses a -- different type than you want. In the SQL command text, attach an -- explicit cast to the parameter symbol to show what data type you will -- send. For example: SELECT * FROM mytable WHERE x = $1::bigint; This -- forces parameter $1 to be treated as bigint, whereas by default it -- would be assigned the same type as x. Forcing the parameter type -- decision, either this way or by specifying a numeric type OID, is -- strongly recommended when sending parameter values in binary format, -- because binary format has less redundancy than text format and so -- there is less chance that the server will detect a type mismatch -- mistake for you. execParams :: Connection -> ByteString -> [Maybe (Oid, ByteString, Format)] -> Format -> IO (Maybe Result) -- | Submits a request to create a prepared statement with the given -- parameters, and waits for completion. -- -- prepare creates a prepared statement for later execution with -- execPrepared. This feature allows commands that will be used -- repeatedly to be parsed and planned just once, rather than each time -- they are executed. prepare is supported only in protocol 3.0 -- and later connections; it will fail when using protocol 2.0. -- -- The function creates a prepared statement named stmtName from the -- query string, which must contain a single SQL command. stmtName can be -- "" to create an unnamed statement, in which case any pre-existing -- unnamed statement is automatically replaced; otherwise it is an error -- if the statement name is already defined in the current session. If -- any parameters are used, they are referred to in the query as $1, $2, -- etc. paramTypes specifies, by Oid, the data types to be -- assigned to the parameter symbols. If paramTypes is Nothing, or -- any particular element in the array is zero, the server assigns a data -- type to the parameter symbol in the same way it would do for an -- untyped literal string. Also, the query can use parameter symbols with -- numbers higher than the length of paramTypes; data types will be -- inferred for these symbols as well. (See describePrepared for a -- means to find out what data types were inferred.) -- -- As with exec, the result is normally a Result whose -- contents indicate server-side success or failure. A Nothing -- result indicates out-of-memory or inability to send the command at -- all. Use errorMessage to get more information about such -- errors. -- -- Prepared statements for use with execPrepared can also be -- created by executing SQL PREPARE statements. (But prepare is -- more flexible since it does not require parameter types to be -- pre-specified.) Also, although there is no libpq function for deleting -- a prepared statement, the SQL DEALLOCATE statement can be used for -- that purpose. prepare :: Connection -> ByteString -> ByteString -> Maybe [Oid] -> IO (Maybe Result) -- | Sends a request to execute a prepared statement with given parameters, -- and waits for the result. -- -- execPrepared is like execParams, but the command to be -- executed is specified by naming a previously-prepared statement, -- instead of giving a query string. This feature allows commands that -- will be used repeatedly to be parsed and planned just once, rather -- than each time they are executed. The statement must have been -- prepared previously in the current session. execPrepared is -- supported only in protocol 3.0 and later connections; it will fail -- when using protocol 2.0. -- -- The parameters are identical to execParams, except that the -- name of a prepared statement is given instead of a query string, and -- the paramTypes parameter is not present (it is not needed since the -- prepared statement's parameter types were determined when it was -- created). execPrepared :: Connection -> ByteString -> [Maybe (ByteString, Format)] -> Format -> IO (Maybe Result) -- | Submits a request to obtain information about the specified prepared -- statement, and waits for completion. -- -- describePrepared allows an application to obtain information -- about a previously prepared statement. describePrepared is -- supported only in protocol 3.0 and later connections; it will fail -- when using protocol 2.0. -- -- stmtName can be empty to reference the unnamed statement, otherwise it -- must be the name of an existing prepared statement. On success, a -- Result with status CommandOk is returned. The functions -- nparams and paramtype can be applied to this -- Result to obtain information about the parameters of the -- prepared statement, and the functions nfields, fname, -- ftype, etc provide information about the result columns (if -- any) of the statement. describePrepared :: Connection -> ByteString -> IO (Maybe Result) -- | Submits a request to obtain information about the specified portal, -- and waits for completion. -- -- describePortal allows an application to obtain information -- about a previously created portal. (libpq does not provide any direct -- access to portals, but you can use this function to inspect the -- properties of a cursor created with a DECLARE CURSOR SQL command.) -- describePortal is supported only in protocol 3.0 and later -- connections; it will fail when using protocol 2.0. -- -- portalName can be empty to reference the unnamed portal, otherwise it -- must be the name of an existing portal. On success, a Result -- with status CommandOk is returned. The functions -- nfields, fname, ftype, etc can be applied to the -- Result to obtain information about the result columns (if any) -- of the portal. describePortal :: Connection -> ByteString -> IO (Maybe Result) data ExecStatus -- | The string sent to the server was empty. EmptyQuery :: ExecStatus -- | Successful completion of a command returning no data. CommandOk :: ExecStatus -- | Successful completion of a command returning data (such as a SELECT or -- SHOW). TuplesOk :: ExecStatus -- | Copy Out (from server) data transfer started. CopyOut :: ExecStatus -- | Copy In (to server) data transfer started. CopyIn :: ExecStatus -- | The server's response was not understood. BadResponse :: ExecStatus -- | A nonfatal error (a notice or warning) occurred. NonfatalError :: ExecStatus -- | A fatal error occurred. FatalError :: ExecStatus -- | Returns the result status of the command. resultStatus :: Result -> IO ExecStatus -- | Converts the ExecStatus returned by resultStatus into a -- string describing the status code. The caller should not free the -- result. resStatus :: ExecStatus -> IO ByteString -- | Returns the error message most recently generated by an operation on -- the connection. resultErrorMessage :: Result -> IO (Maybe ByteString) data FieldCode -- | The severity; the field contents are ERROR, FATAL, or PANIC (in an -- error message), or WARNING, NOTICE, DEBUG, INFO, or LOG (in a notice -- message), or a localized translation of one of these. Always present. DiagSeverity :: FieldCode -- | The SQLSTATE code for the error. The SQLSTATE code identifies the type -- of error that has occurred; it can be used by front-end applications -- to perform specific operations (such as error handling) in response to -- a particular database error. For a list of the possible SQLSTATE -- codes, see Appendix A. This field is not localizable, and is always -- present. DiagSqlstate :: FieldCode -- | The primary human-readable error message (typically one line). Always -- present. DiagMessagePrimary :: FieldCode -- | Detail: an optional secondary error message carrying more detail about -- the problem. Might run to multiple lines. DiagMessageDetail :: FieldCode -- | Hint: an optional suggestion what to do about the problem. This is -- intended to differ from detail in that it offers advice (potentially -- inappropriate) rather than hard facts. Might run to multiple lines. DiagMessageHint :: FieldCode -- | A string containing a decimal integer indicating an error cursor -- position as an index into the original statement string. The first -- character has index 1, and positions are measured in characters not -- bytes. DiagStatementPosition :: FieldCode -- | This is defined the same as the DiagStatementPosition field, -- but it is used when the cursor position refers to an internally -- generated command rather than the one submitted by the client. The -- DiagInternalQuery field will always appear when this field -- appears. DiagInternalPosition :: FieldCode -- | The text of a failed internally-generated command. This could be, for -- example, a SQL query issued by a PL/pgSQL function. DiagInternalQuery :: FieldCode -- | An indication of the context in which the error occurred. Presently -- this includes a call stack traceback of active procedural language -- functions and internally-generated queries. The trace is one entry per -- line, most recent first. DiagContext :: FieldCode -- | The file name of the source-code location where the error was -- reported. DiagSourceFile :: FieldCode -- | The line number of the source-code location where the error was -- reported. DiagSourceLine :: FieldCode -- | The name of the source-code function reporting the error. DiagSourceFunction :: FieldCode -- | Returns an individual field of an error report. -- -- fieldcode is an error field identifier; see the symbols listed below. -- Nothing is returned if the PGresult is not an error or warning -- result, or does not include the specified field. Field values will -- normally not include a trailing newline. -- -- The client is responsible for formatting displayed information to meet -- its needs; in particular it should break long lines as needed. Newline -- characters appearing in the error message fields should be treated as -- paragraph breaks, not line breaks. -- -- Errors generated internally by libpq will have severity and primary -- message, but typically no other fields. Errors returned by a -- pre-3.0-protocol server will include severity and primary message, and -- sometimes a detail message, but no other fields. -- -- Note that error fields are only available from Result objects, -- not Connection objects; there is no errorField function. resultErrorField :: Result -> FieldCode -> IO (Maybe ByteString) -- | Frees the memory associated with a result. Note that using this -- function correctly is especially tricky; you need to ensure that no -- references to the result. This means no references to a value returned -- by getvalue, no references hiding inside an unevaluated thunk, -- etc. Improper use of this function is likely to cause a segfault. -- Also, the use of this function is not strictly necessary; the memory -- will get freed by the garbage collector when there are no more -- references to the result. unsafeFreeResult :: Result -> IO () -- | Returns the number of rows (tuples) in the query result. Because it -- returns an integer result, large result sets might overflow the return -- value on 32-bit operating systems. ntuples :: Result -> IO Row -- | Returns the number of columns (fields) in each row of the query -- result. nfields :: Result -> IO Column newtype Row Row :: CInt -> Row newtype Column Col :: CInt -> Column toRow :: Integral a => a -> Row toColumn :: Integral a => a -> Column -- | Returns the column name associated with the given Column -- number. Column numbers start at 0. fname :: Result -> Column -> IO (Maybe ByteString) -- | Returns the column number associated with the given column name. fnumber :: Result -> ByteString -> IO (Maybe Column) -- | Returns the OID of the table from which the given column was fetched. -- Column numbers start at 0. ftable :: Result -> Column -> IO Oid -- | Returns the column number (within its table) of the column making up -- the specified query result column. Query-result column numbers start -- at 0, but table columns have nonzero numbers. ftablecol :: Result -> Column -> IO Column -- | Returns the Format of the given column. Column numbers start at -- 0. fformat :: Result -> Column -> IO Format -- | Returns the data type associated with the given column number. The -- Oid returned is the internal OID number of the type. Column -- numbers start at 0. -- -- You can query the system table pg_type to obtain the names and -- properties of the various data types. The OIDs of the built-in data -- types are defined in the file srcincludecatalog/pg_type.h in -- the source tree. ftype :: Result -> Column -> IO Oid -- | Returns the type modifier of the column associated with the given -- column number. Column numbers start at 0. -- -- The interpretation of modifier values is type-specific; they typically -- indicate precision or size limits. The value -1 is used to indicate -- no information available. Most data types do not use modifiers, -- in which case the value is always -1. fmod :: Result -> Column -> IO Int -- | Returns the size in bytes of the column associated with the given -- column number. Column numbers start at 0. -- -- fsize returns the space allocated for this column in a database -- row, in other words the size of the server's internal representation -- of the data type. (Accordingly, it is not really very useful to -- clients.) A negative value indicates the data type is variable-length. fsize :: Result -> Column -> IO Int -- | Returns a single field value of one row of a PGresult. Row and column -- numbers start at 0. -- -- For convenience, this binding uses getisnull and -- getlength to help construct the result. -- -- Note: The ByteString returned holds a reference to the -- Result. As long as ByteString is live, the Result will not be garbage -- collected. getvalue' returns a copy of the data. getvalue :: Result -> Row -> Column -> IO (Maybe ByteString) -- | Returns a copy of a single field value of one row of a PGresult. Row -- and column numbers start at 0. -- -- For convenience, this binding uses getisnull and -- getlength to help construct the result. getvalue' :: Result -> Row -> Column -> IO (Maybe ByteString) -- | Tests a field for a null value. Row and column numbers start at 0. getisnull :: Result -> Row -> Column -> IO Bool -- | Returns the actual length of a field value in bytes. Row and column -- numbers start at 0. -- -- This is the actual data length for the particular data value, that is, -- the size of the object pointed to by getvalue. For text data -- format this is the same as strlen(). For binary format this is -- essential information. Note that one should not rely on fsize -- to obtain the actual data length. getlength :: Result -> Row -> Column -> IO Int -- | Returns the number of parameters of a prepared statement. -- -- This function is only useful when inspecting the result of -- PQdescribePrepared. For other types of queries it will return zero. nparams :: Result -> IO Int -- | Returns the data type of the indicated statement parameter. Parameter -- numbers start at 0. -- -- This function is only useful when inspecting the result of -- describePrepared. For other types of queries it will return -- zero. paramtype :: Result -> Int -> IO Oid -- | Returns the command status tag from the SQL command that generated the -- PGresult. -- -- Commonly this is just the name of the command, but it might include -- additional data such as the number of rows processed. cmdStatus :: Result -> IO (Maybe ByteString) -- | Returns the number of rows affected by the SQL command. -- -- This function returns a string containing the number of rows affected -- by the SQL statement that generated the Result. This function -- can only be used following the execution of a SELECT, CREATE TABLE AS, -- INSERT, UPDATE, DELETE, MOVE, FETCH, or COPY statement, or an EXECUTE -- of a prepared query that contains an INSERT, UPDATE, or DELETE -- statement. If the command that generated the Result was -- anything else, cmdTuples returns an empty string. cmdTuples :: Result -> IO (Maybe ByteString) -- | Returns the Oid of the inserted row, if the SQL command was an -- INSERT that inserted exactly one row into a table that has OIDs, or a -- EXECUTE of a prepared query containing a suitable INSERT statement. -- Otherwise, this function returns Nothing. This function will -- also return Nothing if the table affected by the INSERT -- statement does not contain OIDs. oidValue :: Result -> IO (Maybe Oid) -- | Escapes a string for use within an SQL command. This is useful when -- inserting data values as literal constants in SQL commands. Certain -- characters (such as quotes and backslashes) must be escaped to prevent -- them from being interpreted specially by the SQL parser. escapeStringConn :: Connection -> ByteString -> IO (Maybe ByteString) -- | Escapes binary data for use within an SQL command with the type bytea. -- As with escapeStringConn, this is only used when inserting data -- directly into an SQL command string. escapeByteaConn :: Connection -> ByteString -> IO (Maybe ByteString) -- | Converts a ByteString representation of binary data into -- binary data - the reverse of PQescapeByteaConn. This is -- needed when retrieving bytea data in text format, but not when -- retrieving it in binary format. -- -- The parameter points to a string such as might be returned by -- getvalue when applied to a bytea column. unescapeBytea -- converts this string representation into its binary representation. It -- returns a ByteString, or Nothing on error. -- -- This conversion is not exactly the inverse of escapeByteaConn, -- because the string is not expected to be escaped when received -- from getvalue. In particular this means there is no need for -- string quoting considerations, and so no need for a Connection -- parameter. unescapeBytea :: ByteString -> IO (Maybe ByteString) data CopyInResult -- | The data was sent. CopyInOk :: CopyInResult -- | An error occurred (use errorMessage to retrieve details). CopyInError :: CopyInResult -- | The data was not sent because the attempt would block (this case is -- only possible if the connection is in nonblocking mode) Wait for -- write-ready (e.g. by using threadWaitWrite on the -- socket) and try again. CopyInWouldBlock :: CopyInResult -- | Send raw COPY data to the server during the CopyIn -- state. putCopyData :: Connection -> ByteString -> IO CopyInResult -- | Send end-of-data indication to the server during the CopyIn -- state. -- -- -- -- After putCopyEnd returns CopyOk, call getResult -- to obtain the final result status of the COPY command. Then -- return to normal operation. putCopyEnd :: Connection -> Maybe ByteString -> IO CopyInResult data CopyOutResult -- | Data representing a single row of the result CopyOutRow :: !ByteString -> CopyOutResult -- | A complete row is not yet available. This case is only possible when -- getCopyData is has the async parameter set to True. CopyOutWouldBlock :: CopyOutResult -- | No more rows are available CopyOutDone :: CopyOutResult -- | An error occurred (e.g. the connection is not in the CopyOut -- state). Call errorMessage for more information. CopyOutError :: CopyOutResult -- | Receive raw COPY data from the server during the -- CopyOut state. The boolean parameter determines whether or not -- the call will block while waiting for data. getCopyData :: Connection -> Bool -> IO CopyOutResult -- | Submits a command to the server without waiting for the result(s). -- True is returned if the command was successfully dispatched and -- False if not (in which case, use errorMessage to get -- more information about the failure). sendQuery :: Connection -> ByteString -> IO Bool -- | Submits a command and separate parameters to the server without -- waiting for the result(s). sendQueryParams :: Connection -> ByteString -> [Maybe (Oid, ByteString, Format)] -> Format -> IO Bool -- | Sends a request to create a prepared statement with the given -- parameters, without waiting for completion. sendPrepare :: Connection -> ByteString -> ByteString -> Maybe [Oid] -> IO Bool -- | Sends a request to execute a prepared statement with given parameters, -- without waiting for the result(s). sendQueryPrepared :: Connection -> ByteString -> [Maybe (ByteString, Format)] -> Format -> IO Bool -- | Submits a request to obtain information about the specified prepared -- statement, without waiting for completion. -- -- This is an asynchronous version of describePrepared: it returns -- True if it was able to dispatch the request, and False -- if not. After a successful call, call getResult to obtain the -- results. The function's parameters are handled identically to -- describePrepared. Like describePrepared, it will not -- work on 2.0-protocol connections. sendDescribePrepared :: Connection -> ByteString -> IO Bool -- | Submits a request to obtain information about the specified portal, -- without waiting for completion. -- -- This is an asynchronous version of describePortal: it returns -- True if it was able to dispatch the request, and False -- if not. After a successful call, call getResult to obtain the -- results. The function's parameters are handled identically to -- describePortal. Like describePortal, it will not work on -- 2.0-protocol connections. sendDescribePortal :: Connection -> ByteString -> IO Bool -- | Waits for the next result from a prior sendQuery, -- sendQueryParams, sendPrepare, or -- sendQueryPrepared call, and returns it. A null pointer is -- returned when the command is complete and there will be no more -- results. getResult :: Connection -> IO (Maybe Result) -- | If input is available from the server, consume it. -- -- consumeInput normally returns True indicating no -- error, but returns False if there was some kind of trouble -- (in which case errorMessage can be consulted). Note that the -- result does not say whether any input data was actually collected. -- After calling consumeInput, the application can check -- isBusy and/or notifies to see if their state has -- changed. consumeInput :: Connection -> IO Bool -- | Returns True if a command is busy, that is, getResult would block -- waiting for input. A False return indicates that getResult can be -- called with assurance of not blocking. -- -- isBusy will not itself attempt to read data from the server; -- therefore consumeInput must be invoked first, or the busy state -- will never end. isBusy :: Connection -> IO Bool -- | Sets the nonblocking status of the connection. setnonblocking :: Connection -> Bool -> IO Bool -- | Returns the blocking status of the database connection. isnonblocking :: Connection -> IO Bool data FlushStatus FlushOk :: FlushStatus FlushFailed :: FlushStatus FlushWriting :: FlushStatus -- | Attempts to flush any queued output data to the server. Returns -- FlushOk if successful (or if the send queue is empty), -- FlushFailed if it failed for some reason, or -- FlushWriting if it was unable to send all the data in the send -- queue yet (this case can only occur if the connection is nonblocking). flush :: Connection -> IO FlushStatus -- | Contains the information needed to cancel a command issued through a -- particular database connection. data Cancel -- | Creates a data structure containing the information needed to cancel a -- command issued through a particular database connection. -- -- getCancel creates a Cancel object given a -- Connection. It will return Nothing if the given conn is -- an invalid connection. getCancel :: Connection -> IO (Maybe Cancel) -- | Requests that the server abandon processing of the current command. -- -- The return value is 'Right ()' if the cancel request was successfully -- dispatched and if not, 'Left B.ByteString' containing an error message -- explaining why not. -- -- Successful dispatch is no guarantee that the request will have any -- effect, however. If the cancellation is effective, the current command -- will terminate early and return an error result. If the cancellation -- fails (say, because the server was already done processing the -- command), then there will be no visible result at all. cancel :: Cancel -> IO (Either ByteString ()) data Notify Notify :: ByteString -> CPid -> ByteString -> Notify -- | notification channel name notifyRelname :: Notify -> ByteString -- | process ID of notifying server process notifyBePid :: Notify -> CPid -- | notification payload string notifyExtra :: Notify -> ByteString -- | Returns the next notification from a list of unhandled notification -- messages received from the server. It returns a Nothing if -- there are no pending notifications. Once a notification is returned -- from notifies, it is considered handled and will be removed from the -- list of notifications. notifies :: Connection -> IO (Maybe Notify) -- | Returns the client encoding. clientEncoding :: Connection -> IO ByteString -- | Sets the client encoding. setClientEncoding :: Connection -> ByteString -> IO Bool data Verbosity ErrorsTerse :: Verbosity ErrorsDefault :: Verbosity ErrorsVerbose :: Verbosity -- | Determines the verbosity of messages returned by errorMessage -- and resultErrorMessage. -- -- setErrorVerbosity sets the verbosity mode, returning the -- connection's previous setting. In ErrorsTerse mode, returned -- messages include severity, primary text, and position only; this will -- normally fit on a single line. The default mode produces messages that -- include the above plus any detail, hint, or context fields (these -- might span multiple lines). The ErrorsVerbose mode includes all -- available fields. Changing the verbosity does not affect the messages -- available from already-existing Result objects, only -- subsequently-created ones. setErrorVerbosity :: Connection -> Verbosity -> IO Verbosity -- | LoFd is a Large Object (pseudo) File Descriptor. It is understood by -- libpq but not by operating system calls. newtype LoFd LoFd :: CInt -> LoFd -- | Creates a new large object, returns the Object ID of the newly created -- object. loCreat :: Connection -> IO (Maybe Oid) -- | Creates a new large object with a particular Object ID. Returns -- Nothing if the requested Object ID is already in use by some -- other large object or other failure. If invalidOid is used as a -- parameter, then loCreate will assign an unused Oid. loCreate :: Connection -> Oid -> IO (Maybe Oid) -- | Imports an operating system file as a large object. Note that the file -- is read by the client interface library, not by the server; so it must -- exist in the client file system and be readable by the client -- application. loImport :: Connection -> FilePath -> IO (Maybe Oid) -- | Imports an operating system file as a large object with the given -- Object ID. Combines the behavior of loImport and -- loCreate loImportWithOid :: Connection -> FilePath -> Oid -> IO (Maybe Oid) -- | Exports a large object into a operating system file. Note that the -- file is written by the client interface library, not the server. -- Returns 'Just ()' on success, Nothing on failure. loExport :: Connection -> Oid -> FilePath -> IO (Maybe ()) -- | Opens an existing large object for reading or writing. The Oid -- specifies the large object to open. A large object cannot be opened -- before it is created. A large object descriptor is returned for later -- use in loRead, loWrite, loSeek, loTell, -- and loClose. The descriptor is only valid for the duration of -- the current transation. On failure, Nothing is returned. -- -- The server currently does not distinguish between WriteMode and -- ReadWriteMode; write-only modes are not enforced. However there -- is a significant difference between ReadMode and the other -- modes: with ReadMode you cannot write on the descriptor, and -- the data read from it will reflect the contents of the large object at -- the time of the transaction snapshot that was active when -- loOpen was executed, regardless of later writes by this or -- other transactions. Reading from a descriptor opened in -- WriteMode, ReadWriteMode, or AppendMode returns -- data that reflects all writes of other committed transactions as well -- as the writes of the current transaction. This is similar to the -- behavior of REPEATABLE READ versus READ COMMITTED -- transaction modes for ordinary SQL SELECT commands. loOpen :: Connection -> Oid -> IOMode -> IO (Maybe LoFd) -- | loWrite conn fd buf writes the bytestring buf to the -- large object descriptor fd. The number of bytes actually -- written is returned. In the event of an error, Nothing is -- returned. loWrite :: Connection -> LoFd -> ByteString -> IO (Maybe Int) -- | loRead conn fd len reads up to len bytes from the -- large object descriptor fd. In the event of an error, -- Nothing is returned. loRead :: Connection -> LoFd -> Int -> IO (Maybe ByteString) -- | Changes the current read or write location associated with a large -- object descriptor. The return value is the new location pointer, or -- Nothing on error. loSeek :: Connection -> LoFd -> SeekMode -> Int -> IO (Maybe Int) -- | Obtains the current read or write location of a large object -- descriptor. loTell :: Connection -> LoFd -> IO (Maybe Int) -- | Truncates a large object to a given length. If the length is greater -- than the current large object, then the large object is extended with -- null bytes. ('\x00') -- -- The file offest is not changed. -- -- loTruncate is new as of PostgreSQL 8.3; if this function is run -- against an older server version, it will fail and return -- Nothing loTruncate :: Connection -> LoFd -> Int -> IO (Maybe ()) -- | Closes a large object descriptor. Any large object descriptors that -- remain open at the end of a transaction will be closed automatically. loClose :: Connection -> LoFd -> IO (Maybe ()) -- | Removes a large object from the database. loUnlink :: Connection -> Oid -> IO (Maybe ()) instance Eq Connection instance Eq PollingStatus instance Show PollingStatus instance Eq ConnStatus instance Show ConnStatus instance Eq TransactionStatus instance Show TransactionStatus instance Eq Result instance Show Result instance Eq Format instance Ord Format instance Show Format instance Enum Format instance Eq Oid instance Ord Oid instance Read Oid instance Show Oid instance Storable Oid instance Eq ExecStatus instance Show ExecStatus instance Eq FieldCode instance Show FieldCode instance Eq Column instance Ord Column instance Show Column instance Enum Column instance Num Column instance Eq Row instance Ord Row instance Show Row instance Enum Row instance Num Row instance Eq CopyInResult instance Show CopyInResult instance Show CopyOutResult instance Eq FlushStatus instance Show FlushStatus instance Eq Cancel instance Show Cancel instance Show Notify instance Eq Verbosity instance Show Verbosity instance Eq LoFd instance Ord LoFd instance Show LoFd instance Enum Verbosity instance Storable Notify instance Enum FieldCode instance Enum ExecStatus