SAVEPOINT

Capella Operational

reference

The SAVEPOINT statement enables you to set a savepoint within a transaction.

Purpose

The SAVEPOINT statement enables you to set a savepoint within an ACID transaction. Refer to SQL++ Support for Couchbase Transactions for further information.

This statement may only be used within a transaction.

Syntax

savepoint ::= 'SAVEPOINT' savepointname

savepointname: An identifier specifying a name for the savepoint.

If a savepoint with the same name already exists, the existing savepoint is replaced.

Example

If you want to try this example, first refer to Preparation to set up your environment.

Example 1. Set savepoints

Transaction

-- Start the transaction
BEGIN WORK;

-- Specify transaction settings
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;

-- Create a booking document
UPSERT INTO bookings
VALUES("bf7ad6fa-bdb9-4099-a840-196e47179f03", {
  "date": "07/24/2021",
  "flight": "WN533",
  "flighttime": 7713,
  "price": 964.13,
  "route": "63986"
});

-- Set a savepoint
SAVEPOINT s1;

-- Update the booking document to include a user
UPDATE bookings AS b
SET b.`user` = "0"
WHERE META(b).id = "bf7ad6fa-bdb9-4099-a840-196e47179f03";

-- Check the content of the booking and user
SELECT b.*, u.name
FROM bookings b
JOIN users u
ON b.`user` = META(u).id
WHERE META(b).id = "bf7ad6fa-bdb9-4099-a840-196e47179f03";

-- Set a second savepoint
SAVEPOINT s2;

-- Update the booking documents to change the user
UPDATE bookings AS b
SET b.`user` = "1"
WHERE META(b).id = "bf7ad6fa-bdb9-4099-a840-196e47179f03";

-- Check the content of the booking and user
SELECT b.*, u.name
FROM bookings b
JOIN users u
ON b.`user` = META(u).id
WHERE META(b).id = "bf7ad6fa-bdb9-4099-a840-196e47179f03";

-- Roll back the transaction to the second savepoint
ROLLBACK TRAN TO SAVEPOINT s2;

-- Check the content of the booking and user again
SELECT b.*, u.name
FROM bookings b
JOIN users u
ON b.`user` = META(u).id
WHERE META(b).id = "bf7ad6fa-bdb9-4099-a840-196e47179f03";

-- Commit the transaction
COMMIT WORK;

Results

[
  {
    "batchQuery": "-- Start the transaction\nBEGIN WORK;",
    "batchQueryResult": [
      {
        "txid": "d3bbf182-1179-42ba-8900-eb20fda69e42" (1)
      }
    ]
  },
  {
    "batchQuery": "\n\n-- Specify transaction settings\nSET TRANSACTION ISOLATION LEVEL READ COMMITTED;",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Create a booking document\nUPSERT INTO bookings\nVALUES(\"bf7ad6fa-bdb9-4099-a840-196e47179f03\", {\n  \"date\": \"07/24/2021\",\n  \"flight\": \"WN533\",\n  \"flighttime\": 7713,\n  \"price\": 964.13,\n  \"route\": \"63986\"\n});",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Set a savepoint\nSAVEPOINT s1;",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Update the booking document to include a user\nUPDATE bookings AS b\nSET b.`user` = \"0\"\nWHERE META(b).id = \"bf7ad6fa-bdb9-4099-a840-196e47179f03\";",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Check the content of the booking and user\nSELECT b.*, u.name\nFROM bookings b\nJOIN users u\nON b.`user` = META(u).id\nWHERE META(b).id = \"bf7ad6fa-bdb9-4099-a840-196e47179f03\";",
    "batchQueryResult": [
      {
        "date": "07/24/2021",
        "flight": "WN533",
        "flighttime": 7713,
        "name": "Keon Hoppe",
        "price": 964.13,
        "route": "63986",
        "user": "0" (2)
      }
    ]
  },
  {
    "batchQuery": "\n\n-- Set a second savepoint\nSAVEPOINT s2;",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Update the booking documents to change the user\nUPDATE bookings AS b\nSET b.`user` = \"1\"\nWHERE META(b).id = \"bf7ad6fa-bdb9-4099-a840-196e47179f03\";",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Check the content of the booking and user\nSELECT b.*, u.name\nFROM bookings b\nJOIN users u\nON b.`user` = META(u).id\nWHERE META(b).id = \"bf7ad6fa-bdb9-4099-a840-196e47179f03\";",
    "batchQueryResult": [
      {
        "date": "07/24/2021",
        "flight": "WN533",
        "flighttime": 7713,
        "name": "Rigoberto Bernier",
        "price": 964.13,
        "route": "63986",
        "user": "1" (3)
      }
    ]
  },
  {
    "batchQuery": "\n\n-- Roll back the transaction to the second savepoint\nROLLBACK TRAN TO SAVEPOINT s2;",
    "batchQueryResult": []
  },
  {
    "batchQuery": "\n\n-- Check the content of the booking and user again\nSELECT b.*, u.name\nFROM bookings b\nJOIN users u\nON b.`user` = META(u).id\nWHERE META(b).id = \"bf7ad6fa-bdb9-4099-a840-196e47179f03\";",
    "batchQueryResult": [
      {
        "date": "07/24/2021",
        "flight": "WN533",
        "flighttime": 7713,
        "name": "Keon Hoppe",
        "price": 964.13,
        "route": "63986",
        "user": "0" (4)
      }
    ]
  },
  {
    "batchQuery": "\n\n-- Commit the transaction\nCOMMIT WORK;",
    "batchQueryResult": []
  }
]

1	Beginning a transaction returns a transaction ID.
2	Before setting the second savepoint, the booking document has user `"0"`, name `"Keon Hoppe"`.
3	After setting the second savepoint and performing an update, the booking document has user `"1"`, name `"Rigoberto Bernier"`.
4	After rolling back to the second savepoint, the booking document again has user `"0"`, name `"Keon Hoppe"`.

For an overview of Couchbase transactions, refer to Transactions.
To begin a transaction, refer to BEGIN TRANSACTION.
To specify transaction settings, refer to SET TRANSACTION.
To rollback a transaction, refer to ROLLBACK TRANSACTION.
To commit a transaction, refer to COMMIT TRANSACTION.
Blog post: Couchbase Transactions: Elastic, Scalable, and Distributed.

SAVEPOINT

Purpose

Syntax

Example

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