Settings v2
General settings
logical_replication_mode
: Affects how the program interprets connections and table filter settings and also the requirements to check for in the connections before starting the comparison. Currently the possible values are:off
: Assumes there's no logical replication between the databases.native
: Assumes there's native logical replication between the databases. Enables the use of theTable Filter -> publications
setting to specify the list of tables to use. Requires PostgreSQL 10+ on all databases.pglogical
: Assumes there's pglogical replication between the databases. Enables the use of theTable Filter -> replication_sets
setting to specify the list of tables to use. Also enables the use ofnode_name
to specify the data connections, which requires setting theInitial Connection
that's used to retrieve DSN information of the nodes. Requires thepglogical
extensions to be installed on all databases.bdr
: Assumes all data connections are nodes from the same PGD cluster. Enables use of theTable Filter -> replication_sets
setting to specify the list of tables to use. Also enables the use ofnode_name
to specify the data connections, which requires setting theInitial Connection
that's used to retrieve DSN information of the nodes. Requirespglogical
andbdr
extensions installed on all databases.
all_bdr_nodes
: Iflogical_replication_mode
is set tobdr
, then you can specify only the Initial Connection and let LiveCompare build the connection list based on the current list of active PGD nodes. Default:off
.max_parallel_workers
: Number of parallel processes to consider. Each process works on a table from the queue. Default:2
.Important
Each process keeps N+1 open connections: one to each data connection and another one to the output database.
buffer_size
: Number of rows to retrieve from the tables on every data fetch operation. Default:4096
.log_level
: Verbosity level in the log file. Possible values:debug
,info
,warning
, orerror
. Default:info
.data_fetch_mode
: Affects how LiveCompare fetches data from the database.prepared_statements
: Uses prepared statements (a query withLIMIT
) for data fetch. Only a very small amount of data (buffer_size = 4096
rows by default) is fetched each time, so it has the smallest impact of all three modes, and for the same reason it's the safer fetch mode. Allows asynchronous data fetch (defined byparallel_data_fetch
). For the general use case, this fetch method provides good performance, but a performance decrease can be felt for large tables. This is the default and strongly recommended when server load is medium-high.server_side_cursors_with_hold
: Uses server-side cursorsWITH HOLD
for data fetch. As table data is retrieved in a single transaction, it holds backxmin
and can cause bloat and replication issues and also preventVACUUM
from running well. Also, theWITH HOLD
clause tells Postgres to materialize the query (workers can hang for a few seconds waiting for the data to materialize), so the whole table data consumes RAM and can be stored on Postgres side disk as temporary files. You can reduce all that impact by usingparallel_chunk_rows
(disabled by default), and improve speed by increasingbuffer_size
a little. Allows asynchronous data fetch (defined byparallel_data_fetch
). For the general use case, this fetch method doesn't provide any benefits when compared toprepared_stataments
, but for multiple small tables it's faster. However, this mode is recommended only when load is very low, for example, on tests and migration scenarios.server_side_cursors_without_hold
: Uses server-side cursorsWITHOUT HOLD
for data fetch. Asserver_side_cursors_with_hold
, this mode can also hold backxmin
, thus it potentially can cause bloat,VACUUM
, and replication issues on Postgres. However, such impact is higher becauseWITHOUT HOLD
cursors require an open transaction for the whole comparison session (this requirement will be lifted in later versions). As the snapshot is held for the whole comparison session, comparison results might be helpful depending on your use case. As the query isn't materialized, memory usage and temp file generation remains low. Asynchronous data fetch isn't allowed. In terms of performance, this mode is slower for the general use case, but for large tables it can be the faster. We recommend it when load on the database is low-medium.
Important
The choice of the right data_fetch_mode
for the right scenario
is very important. Using prepared statements has the smallest footprint on the
database server, so it's the safest approach, and it's good for the general use
case. Another point is that prepared statements allow LiveCompare to always see
the latest version of the rows, which might not happen when using server-side
cursors on a busy database. So we recommend using prepared_statements
for
production, high-load servers and either server_side_cursors_*
setting for
testing, migration scenarios, and low-load servers. The best strategy
probably mixes server_side_cursors_without_hold
for very large tables and
prepared_statements
for the remaining tables. The following table shows
a comparison of the cost/benefit ratio.
prepared_statements | server_side_cursors_with_hold | server_side_cursors_without_hold | |
---|---|---|---|
xmin hold | very low | medium | high |
xmin released per | buffer | chunk | whole comparison session |
temp files | very low | very high | low |
memory | very low | high | low |
allows async conns | yes | yes | no |
fastest for | general | small tables | large tables |
recommended load | high | very low | low-medium |
Note about Oracle
For Oracle, the data_fetch_mode
setting is completely
ignored, and data is always fetched from Oracle using a direct query.
Data is taken in chunks of buffer_size
through the client-side cursor.
parallel_chunk_rows
: Minimum number of rows required to consider splitting a table into multiple chunks for parallel comparison. A hash is used to fetch data, so workers don't clash with each other. Each table chunk has no more thanparallel_chunk_rows
rows. Setting it to any value <1 disables table splitting. Default:0
(disabled).
Important
While table splitting can help multiple workers to compare a large table in
parallel, performance for each worker can be affected by
the hash condition being applied to all rows. Depending on the Postgres
configuration (especially with the default of random_page_cost = 4
, which can
be considered too conservative for modern hard drives), the Postgres query
planner can incorrectly prefer bitmap heap scans. If the database is
running on SSD, disabling bitmap heap scan on LiveCompare can significantly
improve the comparison performance. You can do this per connection using the
start_query
setting:
parallel_data_fetch
: Specifies whether data fetch is performed in parallel (that is, using async connections to the databases). Improves performance of multi-way comparison. If any data connections aren't PostgreSQL, then this setting is automatically disabled. It's allowed only whendata_fetch_mode = prepared_statements
ordata_fetch_mode = server_side_cursors_with_hold
. Default:on
.comparison_algorithm
: Affects how LiveCompare works through table rows to compare data. Using hashes is faster than full-row comparison. It can assume one of the following values:full_row
: Disables row comparison using hashes. Full comparison, in this case, is performed by comparing the row column by column.row_hash
: Enables row comparison using hashes and enables table splitting. Tables are split so each worker compares a maximum ofparallel_chunk_rows
per table. Data row is hashed in PostgreSQL, so the comparison is faster thanfull_row
. However, if the hash for a specific row doesn't match, then for that specific row, LiveCompare falls back to thefull_row
algorithm (that is, compare row by row). If any data connection isn't PostgreSQL, then LiveCompare uses a row hash that's defined as the MD5 hash of the concatenated column values of the row being considered, a common hash among the database technologies being compared.block_hash
: Works the same asrow_hash
, but instead of comparing row by row, LiveCompare builds a block hash, that is, a hash of the hashes of all rows in the data buffer that was just fetched (maximum ofbuffer_size
rows). Conceptually it works like a two-level Merkle tree. If the block hash matches, then LiveCompare advances the whole block, which is why this comparison algorithm is faster thanrow_hash
. If block hash doesn't match, then LiveCompare falls back torow_hash
and performs the comparison row by row in the buffer to find the divergent rows. This is the default value.
min_time_between_heart_beats
: Time in seconds to wait before logging a heart beat message to the log. Each worker tracks it separately per round part being compared. Default: 30 seconds.min_time_between_round_saves
: Time in seconds to wait before updating each round state when the comparison algorithm is in progress. A round save can happen only during a heart beat, somin_time_between_round_saves
must be greater than or equal tomin_time_between_heart_beats
. When the round finishes, LiveCompare always updates the round state for that table. Default: 60 seconds.Important
If you cancel execution of LiveCompare by pressing Ctrl-C and start it again, then LiveCompare resumes the round for that table, starting from the point where the round state was saved.
comparison_cost_limit
: If > 0, corresponds to a number of rows each worker processes before taking a nap ofcomparison_cost_delay
seconds. Defaults to 0, meaning that each worker processes rows without taking a nap.comparison_cost_delay
: Ifcomparison_cost_limit > 0
, then this setting specifies how long each worker sleeps. Default:0.0
.stop_after_time
: Time in seconds after which LiveCompare stop as if you press Ctrl-C. You can resume the comparison session that was interrupted, if not finished yet, by passing the session ID as an argument in the command line. Default:stop_after_time = 0
, which means that automatic interruption is disabled.consensus_mode
: Consensus algorithm used by LiveCompare to determine which data connections are divergent. Possible values aresimple_majority
,quorum_based
, orsource_of_truth
. Ifconsensus_mode = source_of_truth
, thendifference_sources_of_truth
must be filled. Default:simple_majority
.difference_required_quorum
: Ifconsensus_mode = quorum_based
, then this setting specifies the minimum quorum required to decide which connections are divergent. Must be a number between 0.0 and 1.0. 0.0 means no connection is required, and 1.0 means all connections are required. Both cases are extreme and we don't recommend using them. The default value is 0.5, and we recommend using a value close to that.difference_sources_of_truth
: Comma-separated list of connections names (or node names, iflogical_replication_mode = bdr
andall_bdr_nodes = on
) to consider as the source of truth. It's used only whenconsensus_mode = source_of_truth
. For example:difference_sources_of_truth = node1,node2
. In this example, either the sectionsnode1 Connection
andnode2 Connection
must be defined in the.ini
file orall_bdr_nodes = on
and only theInitial Connection
is defined, whilenode1
andnode2
must be valid PGD node names.difference_tie_breakers
: Comma-separated list of connection names (or node names, iflogical_replication_mode = bdr
andall_bdr_nodes = on
) to be considered as tie breakers whenever the consensus algorithm finds a tie situation. For example:difference_tie_breakers = node1,node2
. In this example, either the sectionsnode1 Connection
andnode2 Connections
must be defined in the.ini
file orall_bdr_nodes = on
and only theInitial Connection
is defined, whilenode1
andnode2
must be valid PGD node names. Default: Don't consider any connection as tie breaker.difference_statements
: Controls the kind of DML statements for LiveCompare to generate. The value ofdifference_statements
can be one of:all
(default)inserts
updates
deletes
inserts_updates
inserts_deletes
updates_deletes
difference_allow_null_updates
: Determines whether commands likeUPDATE SET col = NULL
are allowed in the difference report. Default:on
.difference_statement_order
: Controls order of DML statements that LiveCompare generates. The value ofdifference_statement_order
can be one of:delete_insert_update
delete_update_insert
(default)insert_update_delete
insert_delete_update
update_insert_delete
update_delete_insert
difference_fix_replication_origin
: When working with PGD databases, for difference, LiveCompare creates a specific replication origin if it doesn't exist yet. It then uses the replication origin to create an apply script with DML fixes. The settingdifference_fix_replication_origin
specifies the name of the replication origin used by LiveCompare. If you don't set any value for this setting, then LiveCompare setsdifference_fix_replication_origin = bdr_local_only_origin
. The replication origin that LiveCompare creates isn't dropped to allow verification after the comparison. However, if needed, you can manually drop the replication origin later. Requireslogical_replication_mode = bdr
.
Important
PGD 3.6.18 introduced the new pre-created bdr_local_only_origin
replication origin to use for applying local-only transactions. So if LiveCompare is connected to PGD 3.6.18, it doesn't create this replication origin, and we recommend you don't try to drop this replication origin.
difference_fix_start_query
: Arbitrary query that's executed at the beginning of the apply script generated by LiveCompare. Additionally, if a PGD comparison is being performed and thedifference_fix_start_query
is empty, then LiveCompare also automatically does the following:- If the divergent connection is PGD 3.6.7, adds
SET LOCAL bdr.xact_replication = off;
- Adds commands that set up transaction to use the replication origin
specified in
difference_fix_replication_origin
- If the divergent connection is PGD 3.6.7, adds
show_progress_bars
: Determines whether to show progress bars in the console output. Disabling this setting might be useful for batch executions. Default:on
.output_schema
: In the output connection, the schema where the comparison report tables are created. Default:livecompare
.hash_column_name
: Every data fetch contains a specific column that's the hash of all actual columns in the row. This setting specifies the name of this column. Default:livecompare_hash
.rownumber_column_name
: Some fetches need to use therow_number()
function value inside a query column. This setting specifies the name of this column. Default:livecompare_rownumber
.fetch_row_origin
: When this setting is enabled, LiveCompare fetches the origin name for each divergent row, which might be useful for debugging purposes. To be enabled, requireslogical_replication_mode
set topglogical
orbdr
. Default:off
.column_intersection
: When this setting is enabled, for a given table that's being compared, LiveCompare works only on the intersection of columns from the table on all connections, ignoring extra columns that might exist on any of the connections. When this setting is disabled, LiveCompare checks if columns are equivalent on the table on all connections and aborts the comparison of the table if there are any column mismatches. Default:off
.
Important
If a table has PK, then the PK columns aren't allowed to be different, even if column_intersection = on
.
ignore_nullable
: For a specific table comparison, if LiveCompare is using a comparison key different from the primary key, then LiveCompare requires all columns to beNOT NULL
ifignore_nullable
is enabled (default). You can override that behavior by settingignore_nullable = off
, which allows LiveCompare to consider null-able columns in the comparison, which in some corner cases can produce false positives.check_uniqueness_enforcement
: If LiveCompare is using a user-defined comparison key or using all columns in the table as a comparison key, then LiveCompare checks for table uniqueness on the comparison key if settingcheck_uniqueness_enforcement
is enabled (default).oracle_ignore_unsortable
: When enabled, tells LiveCompare to ignore columns with Oracle unsortable data types (BLOB, CLOB, NCLOB, BFILE) if column isn't part of the table PK. If enabling this setting, we recommend also enablingcolumn_intersection
.oracle_user_tables_only
: When enabled, tells LiveCompare to fetch table metadata only from the Oracle logged-in user. This approach is faster because it reads, for example, fromsys.user_tables
andsys.user_tab_columns
instead ofsys.all_tables
andsys.all_tab_columns
. Default:off
.oracle_fetch_fk_metadata
: When enabled, tells LiveCompare to fetch foreign-key metadata, which can be a slow operation. Overrides the value of the settingfetch_fk_metadata
on the Oracle connection. Default:off
.schema_qualified_table_names
: Table names are treated as schema qualified when this setting is enabled. Disabling it allows comparing tables without using schema-qualified table names. On Oracle x Postgres comparisons, it requires also enablingoracle_user_tables_only
. On Postgres x Postgres, it allows for comparisons of tables that are under different schemas, even in the same database. Also, whenschema_qualified_table_names
is enabled,Table Filter -> tables
,Row Filter
, andColumn Filter
allow table name without the schema name. Default:on
.force_collate
: When set to a value other thanoff
and to a valid collation name, forces the specified collation name inORDER BY
operations in all Postgres databases being compared. Useful when comparing Postgres databases with different collation or when comparing Oracle and Postgres databases. (In this case, setforce_collate = C
.) Assumes valueC
if comparing mixed technologies (like Oracle versus PostgreSQL) and no collation is specified. Default:off
.work_directory
: Path to theLiveCompare
working directory. The session folder containing output files is created in this directory. Default:.
(current directory).abort_on_setup_error
: When enabled, if LiveCompare encounters any error when trying to set up a table comparison round, the whole comparison session is aborted. Default:off
.
Important
Setting abort_on_setup_error
is considered only during compare
mode. In recheck
mode, LiveCompare always aborts at the first error in setup.
custom_dollar_quoting_delimiter
: When LiveCompare finds differences, it outputs the DML using dollar quoting on strings. The default behavior is to create a random string to compose it. If you want by any means to use a custom one, you can set this parameter as the delimiter to use. You need to set only the constant, not the$
symbols around the constant. Default:off
, which means LiveCompare uses anmd5
hash of the wordLiveCompare
.session_replication_role_replica
: When enabled, LiveCompare uses thesession_replication_role
PostgreSQL setting asreplica
in the output apply scripts. That's useful if you want to prevent firing triggers and rules while applying DML in the nodes with divergences. Enabling it requires a PostgreSQL superuser. Otherwise, it has no effect. Default:off
.split_updates
: When enabled, LiveCompare splitsUPDATE
divergences. That is, instead of generating anUPDATE
DML, it generates correspondingDELETE
andINSERT
in the apply script. Default:off
.float_point_round
: An integer to specify decimal digits that LiveCompare rounds when comparing float-point values coming from the database. Default:-1
, which disables float-point rounding.
Initial Connection
The initial connection is used only when logical_replication_mode
is set to
pglogical
or bdr
. If you set data connections to use only the node_name
setting, it's used when the program starts to fetch DSN
from node names.
technology
: RDBMS technology. Currently the only possible value ispostgresql
.dsn
: PostgreSQL connection string. Ifdsn
is set, thenhost
,port
,dbname
, anduser
are ignored. Thedsn
setting can also have all other parameter key words allowed by libpq.host
: Server address. Leave empty to use the Unix socket connection.port
: Port. Default:5432
.dbname
: Database name. Default:postgres
.user
: Database user. Default:postgres
.application_name
. Application name. Can be used even if you setdsn
instead of all other connection information. Default:livecompare_initial
.
Output Connection
The output connection specifies where LiveCompare creates the comparison report tables.
technology
: RDBMS technology. Currently the only possible value ispostgresql
.dsn
: PostgreSQL connection string. Ifdsn
is set, thenhost
,port
,dbname
, anduser
are ignored. Thedsn
setting can also have all other parameter key words allowed by libpq.host
: Server address. Leave empty to use the Unix socket connection.port
: Port. Default:5432
.dbname
: Database name. Default:postgres
.user
: Database user. Default:postgres
.application_name
. Application name. Can be used even if you setdsn
instead of all other connection information. Default:livecompare_output
.
Data Connection
A data connection is a connection section similar to Initial Connection
and Output Connection
, but LiveCompare effectively fetches and compares
data on the data connections.
Similar to the Initial Connection
and Output Connection
, a data
connection is defined in a named section. The section name is of the
form <Name> Connection
, with <Name>
being any single-word string starting with an
alphabetic character. In this case, whatever you use as Name
is called
the connection ID of the data connection. Each data
connection must also have a unique connection ID in the list of data connections.
If logical_replication_mode = bdr
and all_bdr_nodes = on
, then you don't need
to specify any data connection. LiveCompare builds the
data connection list by fetching PGD metadata from the Initial Connection
.
technology
: RDBMS technology. Currently possible values arepostgresql
ororacle
.node_name
: Name of the node in the cluster. Requireslogical_replication_mode
set topglogical
orbdr
and also requires that theInitial Connection
is filled. Ifnode_name
is set, thendsn
,host
,port
,dbname
, anduser
settings are all ignored.dsn
: PostgreSQL connection string. Ifdsn
is set, thenhost
,port
,dbname
, anduser
are ignored. Thedsn
setting can also have all other parameter key words allowed by libpq.host
: Server address. Leave empty to use the Unix socket connection.port
: Port. Default:5432
.dbname
: Database name. Default:postgres
.service
: Service name, used in Oracle connections. Default:XE
.user
: Database user. Default:postgres
.password
: Plain text password. We don't recommend using this. However, it might be required in some legacy connections.application_name
. Application name. Can be used even if you setdsn
ornode_name
instead of all other connection information. Default:livecompare_<Connection ID>
.start_query
: Arbitrary query that's executed each time a connection to a database is open.fetch_fk_metadata
: Specifies whether LiveCompare gathers metadata about foreign keys on the connection. Default:on
.
Table Filter
If omitted or left empty, this section from the .ini
file means that
LiveCompare executes against all tables in the first database.
If you want LiveCompare to execute against a specific set of tables, there are different ways to specify this:
publications
: You can filter specific publications, and LiveCompare uses only the tables associated with those publications. You can use the variablepublication_name
to build the conditional expression, for example:Requires
logical_replication_mode = native
.replication_sets
: When using pglogical or PGD, you can filter specific replication sets, and LiveCompare works only on the tables associated with those replication sets. You can use the variableset_name
to build the conditional expression, for example:Requires
logical_replication_mode = pglogical
orlogical_replication_mode = bdr
.schemas
: You can filter specific schemas, and LiveCompare works only on the tables that belong to those schemas. You can use the variableschema_name
to build the conditional expression, for example:tables
: The variabletable_name
can help you build a conditional expression to filter only the tables you want LiveCompare to work on, for example:In any conditional expression, escape the
%
character as%%
.
The table name must be schema-qualified, unless schema_qualified_table_names
is disabled. For example, you can filter only a specific list of
tables:
If you disable the general setting schema_qualified_table_names
, then you
must also set an appropriate search_path
for Postgres in the connection
start_query
setting, for example:
Important
If two or more schemas that were set on search_path
contain a table with the same name, just the first one found is considered in the comparison.
The Table Filter
section can have a mix of publications
, replication_sets
,
schemas
, and tables
filters. LiveCompare considers the set of tables
that are in the intersection of all filters you specified. For example:
The table filter is applied in the first database to build the table list. If a table exists in the first database and is being considered in the filter, but it doesn't exist in any other database, then you something like this is added to the logs, and the comparison for that specific table is skipped:
Similarly, if a table exists in any other database but doesn't exist in the first database, then it isn't considered in the comparison, even if you didn't apply any table filter.
A comparison for a specific table is also skipped if the table column names
aren't exactly the same (unless column_intersection
is enabled), and in the
same order. An appropriate message is added to the log file as well.
Currently LiveCompare doesn't check if data types or constraints are the same on both tables.
Important
conflicts
mode doesn't make use of the table filter.
Row Filter
In this section, you can apply a row-level filter to any table, so LiveCompare works only on the rows that satisfy the row filter.
You can write a list of tables under this section, one table per line. All
table names must be schema qualified unless schema_qualified_table_names
is
disabled. For example:
In this case, for the table public.table1
, LiveCompare works only in the
rows that satisfy the clause id = 10
. For the table public.table2
,
only rows that satisfy logdate >= '2000-01-01
are considered in the
comparison.
If you disable the general setting schema_qualified_table_names
, then you
must also set an appropriate search_path
for Postgres in the connection
start_query
setting, for example:
Any kind of SQL condition (same as you put in the WHERE
clause) is
accepted in the same line as the table row filter. For example, if you have a
large table and want to compare only a specific number of IDs, you can
create a temporary table with all the IDs. Then you can use an IN
clause to
emulate a JOIN
, like this:
If a row filter is written incorrectly, then LiveCompare tries to apply the filter but fails. So the comparison for this specific table is skipped, and an exception is written to the log file.
If a table is listed in the Row Filter
section but somehow got filtered out
by the Table Filter
, then the row filter for this table is silently
ignored.
Important
conflicts
mode doesn't make use of the row filter.
Using current timestamp in Row Filter
The Row Filter
is applied differently depending on the data_fetch_mode
:
- On Postgres, setting
data_fetch_mode
toserver_side_cursors_with_hold
orserver_side_cursors_without_hold
causes theRow Filter
to be applied only at the beginning of the table comparison, when the query is executed. This means that using a server-side cursor to fetch data ensures the data is seen as a snapshot of how it was beginning of the comparison. - On Postgres, setting
data_fetch_mode
toprepared_statements
(the default) includes theRow Filter
in the prepared query, which is then executed at every data buffer that's fetched. This means that, if the query usesnow()
,CURRENT_TIMESTAMP
, orSYSDATE
(on EDB Postgres Advanced Server) on theRow Filter
, then when the prepared statement executes, Postgres reevaluates the current timestamp.
So, suppose you're using now()
, CURRENT_TIMESTAMP
, or SYSDATE
on the Row Filter
,
for example:
In this case, you must also use a server-side cursor to ensure the current
timestamp is evaluated only at the beginning of the queries. In other words,
data_fetch_mode
must be set to a value different from
prepared_statements
.
On Oracle, the data_fetch_mode
setting is ignored, and
the query is executed at the beginning. Then data is fetched by way of the client-side
cursor. This approach ensures data is seen as a snapshot of how it was at the beginning
of the comparison. This is a client-side cursor, but the behavior is similar to
using a server-side cursor in Postgres.
Column Filter
In this section, you can apply a column-level filter to any table, so LiveCompare works only on the columns that aren't part of the column filter.
You can write a list of tables under this section, one table per line. All
table names must be schema qualified unless schema_qualified_table_names
is
disabled. For example, suppose that both public.table1
and public.table2
have
the columns column1
, column2
, column3
, column4
, and column5
:
In this case, for the table public.table1
, LiveCompare works only in the
columns column2
, column4
, and column5
, filtering out column1
and column3
.
For the table public.table2
, only the columns column2
, column3
, and
column4
are considered in the comparison, filtering out column1
and column5
.
If you disable the general setting schema_qualified_table_names
, then you
must also set an appropriate search_path
for Postgres in the connection
start_query
setting, for example:
If absent column names are given in the column filter, that is, the column doesn't exist in the given table, then LiveCompare logs a message about the missing columns and ignores them. It uses just the valid ones, if any.
If a table is listed in the Column Filter
section but somehow got filtered
out by the Table Filter
, then the column filter for this table is
silently ignored.
Important
If a column specified in a Column Filter
is part of the table PK, then it isn't ignored in the comparison. LiveCompare logs that and ignores the filter of such a column.
Important
conflicts
mode doesn't make use of the column filter.
Comparison Key
New feature
LiveCompare comparison key support is available in LiveCompare version 2.0 and later.
Similar to the Column Filter
, in this section you can also specify a list
of columns per table. These columns are considered as a comparison key for
the specific table, even if the table has a primary key or UNIQUE
constraint.
For example:
In this example, for table public.table1
, the comparison key is
columns col_a
and col_b
. For table public.table2
, columns c1
and c2
are
considered as a comparison key.
The same behavior about missing columns or filtered out or missing tables that
are explained in Column Filter, also apply to the comparison
key. Similarly, the Comparison Key
section is ignored in conflicts
mode.
Conflicts Filter
In this section, you can specify a filter to use in --conflicts
mode while
fetching conflicts from PGD nodes. You can build any SQL conditional expression
and use these fields in the expression:
origin_node
: The upstream node of the subscription.target_node
: The downstream node of the subscription.local_time
: The timestamp when the conflict occurred in the node.conflict_type
: The type of conflict.conflict_resolution
: The resolution that was applied.nspname
: Schema name of the involved relation.relname
: Relation name of the involved relation.
You must use the conflicts
attribute under the section. For example:
If you add this piece of configuration to your .ini
file, LiveCompare fetches
only conflicts that are of type update_missing
and related to tables under
the schema my_schema
while querying for conflicts in each of the PGD nodes.
Important
This section is exclusively for --conflicts
mode.