logical.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 * logical.h
 *     PostgreSQL logical decoding coordination
 *
 * Copyright (c) 2012-2025, PostgreSQL Global Development Group
 *
 *-------------------------------------------------------------------------
 */
#ifndef LOGICAL_H
#define LOGICAL_H
 
#include "access/xlog.h"
#include "access/xlogreader.h"
#include "replication/output_plugin.h"
#include "replication/slot.h"
 
struct LogicalDecodingContext;
 
typedef void (*LogicalOutputPluginWriterWrite) (struct LogicalDecodingContext *lr,
                                                XLogRecPtr Ptr,
                                                TransactionId xid,
                                                bool last_write
);
 
typedef LogicalOutputPluginWriterWrite LogicalOutputPluginWriterPrepareWrite;
 
typedef void (*LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingContext *lr,
                                                         XLogRecPtr Ptr,
                                                         TransactionId xid,
                                                         bool skipped_xact
);
 
typedef struct LogicalDecodingContext
{
    /* memory context this is all allocated in */
    MemoryContext context;
 
    /* The associated replication slot */
    ReplicationSlot *slot;
 
    /* infrastructure pieces for decoding */
    XLogReaderState *reader;
    struct ReorderBuffer *reorder;
    struct SnapBuild *snapshot_builder;
 
    /*
     * Marks the logical decoding context as fast forward decoding one. Such a
     * context does not have plugin loaded so most of the following properties
     * are unused.
     */
    bool        fast_forward;
 
    OutputPluginCallbacks callbacks;
    OutputPluginOptions options;
 
    /*
     * User specified options
     */
    List       *output_plugin_options;
 
    /*
     * User-Provided callback for writing/streaming out data.
     */
    LogicalOutputPluginWriterPrepareWrite prepare_write;
    LogicalOutputPluginWriterWrite write;
    LogicalOutputPluginWriterUpdateProgress update_progress;
 
    /*
     * Output buffer.
     */
    StringInfo  out;
 
    /*
     * Private data pointer of the output plugin.
     */
    void       *output_plugin_private;
 
    /*
     * Private data pointer for the data writer.
     */
    void       *output_writer_private;
 
    /*
     * Does the output plugin support streaming, and is it enabled?
     */
    bool        streaming;
 
    /*
     * Does the output plugin support two-phase decoding, and is it enabled?
     */
    bool        twophase;
 
    /*
     * Is two-phase option given by output plugin?
     *
     * This flag indicates that the plugin passed in the two-phase option as
     * part of the START_STREAMING command. We can't rely solely on the
     * twophase flag which only tells whether the plugin provided all the
     * necessary two-phase callbacks.
     */
    bool        twophase_opt_given;
 
    /*
     * State for writing output.
     */
    bool        accept_writes;
    bool        prepared_write;
    XLogRecPtr  write_location;
    TransactionId write_xid;
    /* Are we processing the end LSN of a transaction? */
    bool        end_xact;
 
    /* Do we need to process any change in fast_forward mode? */
    bool        processing_required;
} LogicalDecodingContext;
 
 
extern void CheckLogicalDecodingRequirements(void);
 
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
                                                         List *output_plugin_options,
                                                         bool need_full_snapshot,
                                                         XLogRecPtr restart_lsn,
                                                         XLogReaderRoutine *xl_routine,
                                                         LogicalOutputPluginWriterPrepareWrite prepare_write,
                                                         LogicalOutputPluginWriterWrite do_write,
                                                         LogicalOutputPluginWriterUpdateProgress update_progress);
extern LogicalDecodingContext *CreateDecodingContext(XLogRecPtr start_lsn,
                                                     List *output_plugin_options,
                                                     bool fast_forward,
                                                     XLogReaderRoutine *xl_routine,
                                                     LogicalOutputPluginWriterPrepareWrite prepare_write,
                                                     LogicalOutputPluginWriterWrite do_write,
                                                     LogicalOutputPluginWriterUpdateProgress update_progress);
extern void DecodingContextFindStartpoint(LogicalDecodingContext *ctx);
extern bool DecodingContextReady(LogicalDecodingContext *ctx);
extern void FreeDecodingContext(LogicalDecodingContext *ctx);
 
extern void LogicalIncreaseXminForSlot(XLogRecPtr current_lsn,
                                       TransactionId xmin);
extern void LogicalIncreaseRestartDecodingForSlot(XLogRecPtr current_lsn,
                                                  XLogRecPtr restart_lsn);
extern void LogicalConfirmReceivedLocation(XLogRecPtr lsn);
 
extern bool filter_prepare_cb_wrapper(LogicalDecodingContext *ctx,
                                      TransactionId xid, const char *gid);
extern bool filter_by_origin_cb_wrapper(LogicalDecodingContext *ctx, RepOriginId origin_id);
extern void ResetLogicalStreamingState(void);
extern void UpdateDecodingStats(LogicalDecodingContext *ctx);
 
extern bool LogicalReplicationSlotHasPendingWal(XLogRecPtr end_of_wal);
extern XLogRecPtr LogicalSlotAdvanceAndCheckSnapState(XLogRecPtr moveto,
                                                      bool *found_consistent_snapshot);
 
#endif