postgresql/contrib/test_decoding/test_decoding.c
Amit Kapila 45fdc9738b Extend the logical decoding output plugin API with stream methods.
This adds seven methods to the output plugin API, adding support for
streaming changes of large in-progress transactions.

* stream_start
* stream_stop
* stream_abort
* stream_commit
* stream_change
* stream_message
* stream_truncate

Most of this is a simple extension of the existing methods, with
the semantic difference that the transaction (or subtransaction)
is incomplete and may be aborted later (which is something the
regular API does not really need to deal with).

This also extends the 'test_decoding' plugin, implementing these
new stream methods.

The stream_start/start_stop are used to demarcate a chunk of changes
streamed for a particular toplevel transaction.

This commit simply adds these new APIs and the upcoming patch to "allow
the streaming mode in ReorderBuffer" will use these APIs.

Author: Tomas Vondra, Dilip Kumar, Amit Kapila
Reviewed-by: Amit Kapila
Tested-by: Neha Sharma and Mahendra Singh Thalor
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com
2020-07-28 08:09:44 +05:30

719 lines
20 KiB
C

/*-------------------------------------------------------------------------
*
* test_decoding.c
* example logical decoding output plugin
*
* Copyright (c) 2012-2020, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/test_decoding/test_decoding.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_type.h"
#include "replication/logical.h"
#include "replication/origin.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
PG_MODULE_MAGIC;
/* These must be available to dlsym() */
extern void _PG_init(void);
extern void _PG_output_plugin_init(OutputPluginCallbacks *cb);
typedef struct
{
MemoryContext context;
bool include_xids;
bool include_timestamp;
bool skip_empty_xacts;
bool xact_wrote_changes;
bool only_local;
} TestDecodingData;
static void pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
bool is_init);
static void pg_decode_shutdown(LogicalDecodingContext *ctx);
static void pg_decode_begin_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_output_begin(LogicalDecodingContext *ctx,
TestDecodingData *data,
ReorderBufferTXN *txn,
bool last_write);
static void pg_decode_commit_txn(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
static void pg_decode_change(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, Relation rel,
ReorderBufferChange *change);
static void pg_decode_truncate(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
int nrelations, Relation relations[],
ReorderBufferChange *change);
static bool pg_decode_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id);
static void pg_decode_message(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr message_lsn,
bool transactional, const char *prefix,
Size sz, const char *message);
static void pg_decode_stream_start(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_decode_stream_stop(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn);
static void pg_decode_stream_abort(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr abort_lsn);
static void pg_decode_stream_commit(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn);
static void pg_decode_stream_change(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
Relation relation,
ReorderBufferChange *change);
static void pg_decode_stream_message(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr message_lsn,
bool transactional, const char *prefix,
Size sz, const char *message);
static void pg_decode_stream_truncate(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
int nrelations, Relation relations[],
ReorderBufferChange *change);
void
_PG_init(void)
{
/* other plugins can perform things here */
}
/* specify output plugin callbacks */
void
_PG_output_plugin_init(OutputPluginCallbacks *cb)
{
AssertVariableIsOfType(&_PG_output_plugin_init, LogicalOutputPluginInit);
cb->startup_cb = pg_decode_startup;
cb->begin_cb = pg_decode_begin_txn;
cb->change_cb = pg_decode_change;
cb->truncate_cb = pg_decode_truncate;
cb->commit_cb = pg_decode_commit_txn;
cb->filter_by_origin_cb = pg_decode_filter;
cb->shutdown_cb = pg_decode_shutdown;
cb->message_cb = pg_decode_message;
cb->stream_start_cb = pg_decode_stream_start;
cb->stream_stop_cb = pg_decode_stream_stop;
cb->stream_abort_cb = pg_decode_stream_abort;
cb->stream_commit_cb = pg_decode_stream_commit;
cb->stream_change_cb = pg_decode_stream_change;
cb->stream_message_cb = pg_decode_stream_message;
cb->stream_truncate_cb = pg_decode_stream_truncate;
}
/* initialize this plugin */
static void
pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
bool is_init)
{
ListCell *option;
TestDecodingData *data;
data = palloc0(sizeof(TestDecodingData));
data->context = AllocSetContextCreate(ctx->context,
"text conversion context",
ALLOCSET_DEFAULT_SIZES);
data->include_xids = true;
data->include_timestamp = false;
data->skip_empty_xacts = false;
data->only_local = false;
ctx->output_plugin_private = data;
opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
opt->receive_rewrites = false;
foreach(option, ctx->output_plugin_options)
{
DefElem *elem = lfirst(option);
Assert(elem->arg == NULL || IsA(elem->arg, String));
if (strcmp(elem->defname, "include-xids") == 0)
{
/* if option does not provide a value, it means its value is true */
if (elem->arg == NULL)
data->include_xids = true;
else if (!parse_bool(strVal(elem->arg), &data->include_xids))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else if (strcmp(elem->defname, "include-timestamp") == 0)
{
if (elem->arg == NULL)
data->include_timestamp = true;
else if (!parse_bool(strVal(elem->arg), &data->include_timestamp))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else if (strcmp(elem->defname, "force-binary") == 0)
{
bool force_binary;
if (elem->arg == NULL)
continue;
else if (!parse_bool(strVal(elem->arg), &force_binary))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
if (force_binary)
opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
}
else if (strcmp(elem->defname, "skip-empty-xacts") == 0)
{
if (elem->arg == NULL)
data->skip_empty_xacts = true;
else if (!parse_bool(strVal(elem->arg), &data->skip_empty_xacts))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else if (strcmp(elem->defname, "only-local") == 0)
{
if (elem->arg == NULL)
data->only_local = true;
else if (!parse_bool(strVal(elem->arg), &data->only_local))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else if (strcmp(elem->defname, "include-rewrites") == 0)
{
if (elem->arg == NULL)
continue;
else if (!parse_bool(strVal(elem->arg), &opt->receive_rewrites))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not parse value \"%s\" for parameter \"%s\"",
strVal(elem->arg), elem->defname)));
}
else
{
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("option \"%s\" = \"%s\" is unknown",
elem->defname,
elem->arg ? strVal(elem->arg) : "(null)")));
}
}
}
/* cleanup this plugin's resources */
static void
pg_decode_shutdown(LogicalDecodingContext *ctx)
{
TestDecodingData *data = ctx->output_plugin_private;
/* cleanup our own resources via memory context reset */
MemoryContextDelete(data->context);
}
/* BEGIN callback */
static void
pg_decode_begin_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
{
TestDecodingData *data = ctx->output_plugin_private;
data->xact_wrote_changes = false;
if (data->skip_empty_xacts)
return;
pg_output_begin(ctx, data, txn, true);
}
static void
pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
{
OutputPluginPrepareWrite(ctx, last_write);
if (data->include_xids)
appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
else
appendStringInfoString(ctx->out, "BEGIN");
OutputPluginWrite(ctx, last_write);
}
/* COMMIT callback */
static void
pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
if (data->skip_empty_xacts && !data->xact_wrote_changes)
return;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "COMMIT %u", txn->xid);
else
appendStringInfoString(ctx->out, "COMMIT");
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
static bool
pg_decode_filter(LogicalDecodingContext *ctx,
RepOriginId origin_id)
{
TestDecodingData *data = ctx->output_plugin_private;
if (data->only_local && origin_id != InvalidRepOriginId)
return true;
return false;
}
/*
* Print literal `outputstr' already represented as string of type `typid'
* into stringbuf `s'.
*
* Some builtin types aren't quoted, the rest is quoted. Escaping is done as
* if standard_conforming_strings were enabled.
*/
static void
print_literal(StringInfo s, Oid typid, char *outputstr)
{
const char *valptr;
switch (typid)
{
case INT2OID:
case INT4OID:
case INT8OID:
case OIDOID:
case FLOAT4OID:
case FLOAT8OID:
case NUMERICOID:
/* NB: We don't care about Inf, NaN et al. */
appendStringInfoString(s, outputstr);
break;
case BITOID:
case VARBITOID:
appendStringInfo(s, "B'%s'", outputstr);
break;
case BOOLOID:
if (strcmp(outputstr, "t") == 0)
appendStringInfoString(s, "true");
else
appendStringInfoString(s, "false");
break;
default:
appendStringInfoChar(s, '\'');
for (valptr = outputstr; *valptr; valptr++)
{
char ch = *valptr;
if (SQL_STR_DOUBLE(ch, false))
appendStringInfoChar(s, ch);
appendStringInfoChar(s, ch);
}
appendStringInfoChar(s, '\'');
break;
}
}
/* print the tuple 'tuple' into the StringInfo s */
static void
tuple_to_stringinfo(StringInfo s, TupleDesc tupdesc, HeapTuple tuple, bool skip_nulls)
{
int natt;
/* print all columns individually */
for (natt = 0; natt < tupdesc->natts; natt++)
{
Form_pg_attribute attr; /* the attribute itself */
Oid typid; /* type of current attribute */
Oid typoutput; /* output function */
bool typisvarlena;
Datum origval; /* possibly toasted Datum */
bool isnull; /* column is null? */
attr = TupleDescAttr(tupdesc, natt);
/*
* don't print dropped columns, we can't be sure everything is
* available for them
*/
if (attr->attisdropped)
continue;
/*
* Don't print system columns, oid will already have been printed if
* present.
*/
if (attr->attnum < 0)
continue;
typid = attr->atttypid;
/* get Datum from tuple */
origval = heap_getattr(tuple, natt + 1, tupdesc, &isnull);
if (isnull && skip_nulls)
continue;
/* print attribute name */
appendStringInfoChar(s, ' ');
appendStringInfoString(s, quote_identifier(NameStr(attr->attname)));
/* print attribute type */
appendStringInfoChar(s, '[');
appendStringInfoString(s, format_type_be(typid));
appendStringInfoChar(s, ']');
/* query output function */
getTypeOutputInfo(typid,
&typoutput, &typisvarlena);
/* print separator */
appendStringInfoChar(s, ':');
/* print data */
if (isnull)
appendStringInfoString(s, "null");
else if (typisvarlena && VARATT_IS_EXTERNAL_ONDISK(origval))
appendStringInfoString(s, "unchanged-toast-datum");
else if (!typisvarlena)
print_literal(s, typid,
OidOutputFunctionCall(typoutput, origval));
else
{
Datum val; /* definitely detoasted Datum */
val = PointerGetDatum(PG_DETOAST_DATUM(origval));
print_literal(s, typid, OidOutputFunctionCall(typoutput, val));
}
}
}
/*
* callback for individual changed tuples
*/
static void
pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change)
{
TestDecodingData *data;
Form_pg_class class_form;
TupleDesc tupdesc;
MemoryContext old;
data = ctx->output_plugin_private;
/* output BEGIN if we haven't yet */
if (data->skip_empty_xacts && !data->xact_wrote_changes)
{
pg_output_begin(ctx, data, txn, false);
}
data->xact_wrote_changes = true;
class_form = RelationGetForm(relation);
tupdesc = RelationGetDescr(relation);
/* Avoid leaking memory by using and resetting our own context */
old = MemoryContextSwitchTo(data->context);
OutputPluginPrepareWrite(ctx, true);
appendStringInfoString(ctx->out, "table ");
appendStringInfoString(ctx->out,
quote_qualified_identifier(get_namespace_name(get_rel_namespace(RelationGetRelid(relation))),
class_form->relrewrite ?
get_rel_name(class_form->relrewrite) :
NameStr(class_form->relname)));
appendStringInfoChar(ctx->out, ':');
switch (change->action)
{
case REORDER_BUFFER_CHANGE_INSERT:
appendStringInfoString(ctx->out, " INSERT:");
if (change->data.tp.newtuple == NULL)
appendStringInfoString(ctx->out, " (no-tuple-data)");
else
tuple_to_stringinfo(ctx->out, tupdesc,
&change->data.tp.newtuple->tuple,
false);
break;
case REORDER_BUFFER_CHANGE_UPDATE:
appendStringInfoString(ctx->out, " UPDATE:");
if (change->data.tp.oldtuple != NULL)
{
appendStringInfoString(ctx->out, " old-key:");
tuple_to_stringinfo(ctx->out, tupdesc,
&change->data.tp.oldtuple->tuple,
true);
appendStringInfoString(ctx->out, " new-tuple:");
}
if (change->data.tp.newtuple == NULL)
appendStringInfoString(ctx->out, " (no-tuple-data)");
else
tuple_to_stringinfo(ctx->out, tupdesc,
&change->data.tp.newtuple->tuple,
false);
break;
case REORDER_BUFFER_CHANGE_DELETE:
appendStringInfoString(ctx->out, " DELETE:");
/* if there was no PK, we only know that a delete happened */
if (change->data.tp.oldtuple == NULL)
appendStringInfoString(ctx->out, " (no-tuple-data)");
/* In DELETE, only the replica identity is present; display that */
else
tuple_to_stringinfo(ctx->out, tupdesc,
&change->data.tp.oldtuple->tuple,
true);
break;
default:
Assert(false);
}
MemoryContextSwitchTo(old);
MemoryContextReset(data->context);
OutputPluginWrite(ctx, true);
}
static void
pg_decode_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
int nrelations, Relation relations[], ReorderBufferChange *change)
{
TestDecodingData *data;
MemoryContext old;
int i;
data = ctx->output_plugin_private;
/* output BEGIN if we haven't yet */
if (data->skip_empty_xacts && !data->xact_wrote_changes)
{
pg_output_begin(ctx, data, txn, false);
}
data->xact_wrote_changes = true;
/* Avoid leaking memory by using and resetting our own context */
old = MemoryContextSwitchTo(data->context);
OutputPluginPrepareWrite(ctx, true);
appendStringInfoString(ctx->out, "table ");
for (i = 0; i < nrelations; i++)
{
if (i > 0)
appendStringInfoString(ctx->out, ", ");
appendStringInfoString(ctx->out,
quote_qualified_identifier(get_namespace_name(relations[i]->rd_rel->relnamespace),
NameStr(relations[i]->rd_rel->relname)));
}
appendStringInfoString(ctx->out, ": TRUNCATE:");
if (change->data.truncate.restart_seqs
|| change->data.truncate.cascade)
{
if (change->data.truncate.restart_seqs)
appendStringInfoString(ctx->out, " restart_seqs");
if (change->data.truncate.cascade)
appendStringInfoString(ctx->out, " cascade");
}
else
appendStringInfoString(ctx->out, " (no-flags)");
MemoryContextSwitchTo(old);
MemoryContextReset(data->context);
OutputPluginWrite(ctx, true);
}
static void
pg_decode_message(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr lsn, bool transactional,
const char *prefix, Size sz, const char *message)
{
OutputPluginPrepareWrite(ctx, true);
appendStringInfo(ctx->out, "message: transactional: %d prefix: %s, sz: %zu content:",
transactional, prefix, sz);
appendBinaryStringInfo(ctx->out, message, sz);
OutputPluginWrite(ctx, true);
}
/*
* We never try to stream any empty xact so we don't need any special handling
* for skip_empty_xacts in streaming mode APIs.
*/
static void
pg_decode_stream_start(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "opening a streamed block for transaction TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "opening a streamed block for transaction");
OutputPluginWrite(ctx, true);
}
/*
* We never try to stream any empty xact so we don't need any special handling
* for skip_empty_xacts in streaming mode APIs.
*/
static void
pg_decode_stream_stop(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "closing a streamed block for transaction TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "closing a streamed block for transaction");
OutputPluginWrite(ctx, true);
}
/*
* We never try to stream any empty xact so we don't need any special handling
* for skip_empty_xacts in streaming mode APIs.
*/
static void
pg_decode_stream_abort(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr abort_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "aborting streamed (sub)transaction TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "aborting streamed (sub)transaction");
OutputPluginWrite(ctx, true);
}
/*
* We never try to stream any empty xact so we don't need any special handling
* for skip_empty_xacts in streaming mode APIs.
*/
static void
pg_decode_stream_commit(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
XLogRecPtr commit_lsn)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "committing streamed transaction TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "committing streamed transaction");
if (data->include_timestamp)
appendStringInfo(ctx->out, " (at %s)",
timestamptz_to_str(txn->commit_time));
OutputPluginWrite(ctx, true);
}
/*
* In streaming mode, we don't display the changes as the transaction can abort
* at a later point in time. We don't want users to see the changes until the
* transaction is committed.
*/
static void
pg_decode_stream_change(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
Relation relation,
ReorderBufferChange *change)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "streaming change for TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "streaming change for transaction");
OutputPluginWrite(ctx, true);
}
/*
* In streaming mode, we don't display the contents for transactional messages
* as the transaction can abort at a later point in time. We don't want users to
* see the message contents until the transaction is committed.
*/
static void
pg_decode_stream_message(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn, XLogRecPtr lsn, bool transactional,
const char *prefix, Size sz, const char *message)
{
OutputPluginPrepareWrite(ctx, true);
if (transactional)
{
appendStringInfo(ctx->out, "streaming message: transactional: %d prefix: %s, sz: %zu",
transactional, prefix, sz);
}
else
{
appendStringInfo(ctx->out, "streaming message: transactional: %d prefix: %s, sz: %zu content:",
transactional, prefix, sz);
appendBinaryStringInfo(ctx->out, message, sz);
}
OutputPluginWrite(ctx, true);
}
/*
* In streaming mode, we don't display the detailed information of Truncate.
* See pg_decode_stream_change.
*/
static void
pg_decode_stream_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
int nrelations, Relation relations[],
ReorderBufferChange *change)
{
TestDecodingData *data = ctx->output_plugin_private;
OutputPluginPrepareWrite(ctx, true);
if (data->include_xids)
appendStringInfo(ctx->out, "streaming truncate for TXN %u", txn->xid);
else
appendStringInfo(ctx->out, "streaming truncate for transaction");
OutputPluginWrite(ctx, true);
}