pgcopydb compare
pgcopydb compare - Compare source and target databases
The command pgcopydb compare connects to the source and target databases
and executes SQL queries to get Postgres catalog information about the
table, indexes and sequences that are migrated.
The tool then compares either the schema definitions or the data contents of the selected tables, and report success by means of an Unix return code of zero.
At the moment, the pgcopydb compare tool is pretty limited in terms of
schema support: it only covers what pgcopydb needs to know about the
database schema, which isn’t much.
pgcopydb compare: Compare source and target databases
Available commands:
pgcopydb compare
schema Compare source and target schema
data Compare source and target data
pgcopydb compare schema
pgcopydb compare schema - Compare source and target schema
The command pgcopydb compare schema connects to the source and target
databases and executes SQL queries using the Postgres catalogs to get a list
of tables, indexes, constraints and sequences there.
pgcopydb compare schema: Compare source and target schema
usage: pgcopydb compare schema --source ...
--source Postgres URI to the source database
--target Postgres URI to the target database
--dir Work directory to use
pgcopydb compare data
pgcopydb compare data - Compare source and target data
The command pgcopydb compare data connects to the source and target
databases and executes SQL queries using the Postgres catalogs to get a list
of tables, indexes, constraints and sequences there.
Then it uses a SQL query with the following template to compute the row count and a checksum for each table:
/*
* Compute the hashtext of every single row in the table, and aggregate the
* results as a sum of bigint numbers. Because the sum of bigint could
* overflow to numeric, the aggregated sum is then hashed into an MD5
* value: bigint is 64 bits, MD5 is 128 bits.
*
* Also, to lower the chances of a collision, include the row count in the
* computation of the MD5 by appending it to the input string of the MD5
* function.
*/
select count(1) as cnt,
md5(
format(
'%%s-%%s',
sum(hashtext(__COLS__::text)::bigint),
count(1)
)
)::uuid as chksum
from only __TABLE__
Running such a query on a large table can take a lot of time.
pgcopydb compare data: Compare source and target data
usage: pgcopydb compare data --source ...
--source Postgres URI to the source database
--target Postgres URI to the target database
--dir Work directory to use
--json Format the output using JSON
Options
The following options are available to pgcopydb compare schema and pgcopydb
compare data subcommands:
- --source
Connection string to the source Postgres instance. See the Postgres documentation for connection strings for the details. In short both the quoted form
"host=... dbname=..."and the URI formpostgres://user@host:5432/dbnameare supported.- --target
Connection string to the target Postgres instance.
- --dir
During its normal operations pgcopydb creates a lot of temporary files to track sub-processes progress. Temporary files are created in the directory location given by this option, or defaults to
${TMPDIR}/pgcopydbwhen the environment variable is set, or then to/tmp/pgcopydb.- --json
The output of the command is formatted in JSON, when supported. Ignored otherwise.
- --verbose
Increase current verbosity. The default level of verbosity is INFO. In ascending order pgcopydb knows about the following verbosity levels: FATAL, ERROR, WARN, INFO, NOTICE, DEBUG, TRACE.
- --debug
Set current verbosity to DEBUG level.
- --trace
Set current verbosity to TRACE level.
- --quiet
Set current verbosity to ERROR level.
Environment
PGCOPYDB_SOURCE_PGURI
Connection string to the source Postgres instance. When
--sourceis ommitted from the command line, then this environment variable is used.
PGCOPYDB_TARGET_PGURI
Connection string to the target Postgres instance. When
--targetis ommitted from the command line, then this environment variable is used.
Examples
Comparing pgcopydb limited understanding of the schema:
$ pgcopydb compare schema --notice
INFO Running pgcopydb version 0.12.28.g34343c8.dirty from "/Users/dim/dev/PostgreSQL/pgcopydb/src/bin/pgcopydb/pgcopydb"
NOTICE Using work dir "/var/folders/d7/zzxmgs9s16gdxxcm0hs0sssw0000gn/T//pgcopydb"
NOTICE Work directory "/var/folders/d7/zzxmgs9s16gdxxcm0hs0sssw0000gn/T//pgcopydb" already exists
INFO A previous run has run through completion
INFO SOURCE: Connecting to "postgres:///pagila"
INFO Fetched information for 1 extensions
INFO Fetched information for 25 tables, with an estimated total of 5179 tuples and 190 MB
INFO Fetched information for 49 indexes
INFO Fetching information for 16 sequences
NOTICE Skipping target catalog preparation
NOTICE Storing migration schema in JSON file "/var/folders/d7/zzxmgs9s16gdxxcm0hs0sssw0000gn/T//pgcopydb/compare/source-schema.json"
INFO TARGET: Connecting to "postgres:///plop"
INFO Fetched information for 6 extensions
INFO Fetched information for 25 tables, with an estimated total of 5219 tuples and 190 MB
INFO Fetched information for 49 indexes
INFO Fetching information for 16 sequences
NOTICE Skipping target catalog preparation
NOTICE Storing migration schema in JSON file "/var/folders/d7/zzxmgs9s16gdxxcm0hs0sssw0000gn/T//pgcopydb/compare/target-schema.json"
INFO [SOURCE] table: 25 index: 49 sequence: 16
INFO [TARGET] table: 25 index: 49 sequence: 16
NOTICE Matched table "public"."test": 1 columns ok, 0 indexes ok
NOTICE Matched table "public"."rental": 7 columns ok, 3 indexes ok
NOTICE Matched table "public"."film": 14 columns ok, 5 indexes ok
NOTICE Matched table "public"."film_actor": 3 columns ok, 2 indexes ok
NOTICE Matched table "public"."inventory": 4 columns ok, 2 indexes ok
NOTICE Matched table "public"."payment_p2022_03": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."payment_p2022_05": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."payment_p2022_06": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."payment_p2022_04": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."payment_p2022_02": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."payment_p2022_07": 6 columns ok, 0 indexes ok
NOTICE Matched table "public"."customer": 10 columns ok, 4 indexes ok
NOTICE Matched table "public"."address": 8 columns ok, 2 indexes ok
NOTICE Matched table "public"."city": 4 columns ok, 2 indexes ok
NOTICE Matched table "public"."film_category": 3 columns ok, 1 indexes ok
NOTICE Matched table "public"."payment_p2022_01": 6 columns ok, 3 indexes ok
NOTICE Matched table "public"."actor": 4 columns ok, 2 indexes ok
NOTICE Matched table "public"."bar": 2 columns ok, 1 indexes ok
NOTICE Matched table "public"."bin": 2 columns ok, 0 indexes ok
NOTICE Matched table "public"."category": 3 columns ok, 1 indexes ok
NOTICE Matched table "public"."country": 3 columns ok, 1 indexes ok
NOTICE Matched table "public"."foo": 2 columns ok, 1 indexes ok
NOTICE Matched table "public"."staff": 11 columns ok, 1 indexes ok
NOTICE Matched table "public"."language": 3 columns ok, 1 indexes ok
NOTICE Matched table "public"."store": 4 columns ok, 2 indexes ok
NOTICE Matched sequence "public"."actor_actor_id_seq" (last value 200)
NOTICE Matched sequence "public"."address_address_id_seq" (last value 605)
NOTICE Matched sequence "public"."bar_id_seq" (last value 1)
NOTICE Matched sequence "public"."bin_id_seq" (last value 17)
NOTICE Matched sequence "public"."category_category_id_seq" (last value 16)
NOTICE Matched sequence "public"."city_city_id_seq" (last value 600)
NOTICE Matched sequence "public"."country_country_id_seq" (last value 109)
NOTICE Matched sequence "public"."customer_customer_id_seq" (last value 599)
NOTICE Matched sequence "public"."film_film_id_seq" (last value 1000)
NOTICE Matched sequence "public"."foo_id_seq" (last value 1)
NOTICE Matched sequence "public"."inventory_inventory_id_seq" (last value 4581)
NOTICE Matched sequence "public"."language_language_id_seq" (last value 6)
NOTICE Matched sequence "public"."payment_payment_id_seq" (last value 32102)
NOTICE Matched sequence "public"."rental_rental_id_seq" (last value 16053)
NOTICE Matched sequence "public"."staff_staff_id_seq" (last value 2)
NOTICE Matched sequence "public"."store_store_id_seq" (last value 2)
INFO pgcopydb schema inspection is successful
Comparing data:
$ pgcopydb compare data
INFO A previous run has run through completion
INFO SOURCE: Connecting to "postgres:///pagila"
INFO Fetched information for 1 extensions
INFO Fetched information for 25 tables, with an estimated total of 5179 tuples and 190 MB
INFO Fetched information for 49 indexes
INFO Fetching information for 16 sequences
INFO TARGET: Connecting to "postgres:///plop"
INFO Fetched information for 6 extensions
INFO Fetched information for 25 tables, with an estimated total of 5219 tuples and 190 MB
INFO Fetched information for 49 indexes
INFO Fetching information for 16 sequences
INFO Comparing data for 25 tables
ERROR Table "public"."test" has 5173526 rows on source, 5173525 rows on target
ERROR Table "public"."test" has checksum be66f291-2774-9365-400c-1ccd5160bdf on source, 8be89afa-bceb-f501-dc7b-0538dc17fa3 on target
ERROR Table "public"."foo" has 3 rows on source, 2 rows on target
ERROR Table "public"."foo" has checksum a244eba3-376b-75e6-6720-e853b485ef6 on source, 594ae64d-2216-f687-2f11-45cbd9c7153 on target
Table Name | ! | Source Checksum | Target Checksum
-------------------------------+---+--------------------------------------+-------------------------------------
"public"."test" | ! | be66f291-2774-9365-400c-1ccd5160bdf | 8be89afa-bceb-f501-dc7b-0538dc17fa3
"public"."rental" | | e7dfabf3-baa8-473a-8fd3-76d59e56467 | e7dfabf3-baa8-473a-8fd3-76d59e56467
"public"."film" | | c5058d1e-aaf4-f058-6f1e-76d5db63da9 | c5058d1e-aaf4-f058-6f1e-76d5db63da9
"public"."film_actor" | | 7534654a-0bcd-cb27-1a2e-ccd524899a9 | 7534654a-0bcd-cb27-1a2e-ccd524899a9
"public"."inventory" | | 72f9afd8-0064-3642-acd7-9ee1f444efe | 72f9afd8-0064-3642-acd7-9ee1f444efe
"public"."payment_p2022_03" | | dc73311a-2ea2-e933-da80-123b44d06b9 | dc73311a-2ea2-e933-da80-123b44d06b9
"public"."payment_p2022_05" | | e788bf50-9809-9896-8110-91816edcc04 | e788bf50-9809-9896-8110-91816edcc04
"public"."payment_p2022_06" | | 5f650b4c-d491-37ac-6d91-dc2ae484600 | 5f650b4c-d491-37ac-6d91-dc2ae484600
"public"."payment_p2022_04" | | 02beb400-1b82-c9ba-8fe9-690eca2e635 | 02beb400-1b82-c9ba-8fe9-690eca2e635
"public"."payment_p2022_02" | | 97154691-488e-9a36-9a4b-4da7b62dbc0 | 97154691-488e-9a36-9a4b-4da7b62dbc0
"public"."payment_p2022_07" | | c6fdf7ef-4382-b301-41c3-1d190149dc5 | c6fdf7ef-4382-b301-41c3-1d190149dc5
"public"."customer" | | 11973c6a-6df3-c502-5495-64f42e0386c | 11973c6a-6df3-c502-5495-64f42e0386c
"public"."address" | | 8c701dbf-c1ba-f386-a9ae-c3f6e478ba7 | 8c701dbf-c1ba-f386-a9ae-c3f6e478ba7
"public"."city" | | f23ad758-f94a-a8fd-8c3f-25fedcadb06 | f23ad758-f94a-a8fd-8c3f-25fedcadb06
"public"."film_category" | | 4b04cfee-e1bc-718d-d890-afdcd6729ce | 4b04cfee-e1bc-718d-d890-afdcd6729ce
"public"."payment_p2022_01" | | fde341ed-0f3f-23bd-dedd-4e92c5a8e55 | fde341ed-0f3f-23bd-dedd-4e92c5a8e55
"public"."actor" | | b5ea389d-140f-10b4-07b9-a80d634d86b | b5ea389d-140f-10b4-07b9-a80d634d86b
"public"."bar" | | a7cae1c8-ed66-63ba-1b93-7ba7570ef63 | a7cae1c8-ed66-63ba-1b93-7ba7570ef63
"public"."bin" | | 6832546a-333b-3bdb-fdf2-325cc7a028a | 6832546a-333b-3bdb-fdf2-325cc7a028a
"public"."category" | | 082f9cf9-92ab-6d6c-c74a-feb577611cc | 082f9cf9-92ab-6d6c-c74a-feb577611cc
"public"."country" | | a3a0dd4f-68e0-4ca5-33d2-05c9fd60c34 | a3a0dd4f-68e0-4ca5-33d2-05c9fd60c34
"public"."foo" | ! | a244eba3-376b-75e6-6720-e853b485ef6 | 594ae64d-2216-f687-2f11-45cbd9c7153
"public"."staff" | | 3eb5f007-7160-81ba-5aa5-973de3f5c3d | 3eb5f007-7160-81ba-5aa5-973de3f5c3d
"public"."language" | | 58aa8132-11ae-f3bc-fa82-c773bba2032 | 58aa8132-11ae-f3bc-fa82-c773bba2032
"public"."store" | | d8477e63-0661-90a4-03fa-fcc26a95865 | d8477e63-0661-90a4-03fa-fcc26a95865