wallet: Store transactions in a separate sqlite table #33034

achow101 commented at 10:52 PM on July 21, 2025: member

The wallet uses SQLite as a key-value store even though SQLite is a powerful relational database engine. This causes us numerous headaches due to the need to serialize multiple fields together, and since record read from the database during loading can come in any order.

Notably, for transactions, if we were able to load them in the transaction order assigned by the wallet, PRs like #27865 would be a bit simpler and easier to reason about.

This PR makes it possible for us to do that by storing transactions in a separate table. This table has a column for each field in CWalletTx, which lets us use a SQL statement like SELECT * FROM transactions ORDER BY pos which guarantees us the order in which the transactions are loaded into the wallet.

The eventual goal is to use SQLite as a relational database with tables that store our keys and other metadata that can reference each other so that the wallet doesn't just use the database as a storage mechanism. But that is still a work in progress.

This PR makes use of the last client opened features introduced in #32895 to determine when the old record style needs to be upgraded to the new transactions table. This should give us sufficient upgrade-downgrade-upgrade handling to not lose any funds.

Depends on #32763, #32895, #33033

DrahtBot added the label Wallet on Jul 21, 2025

DrahtBot commented at 10:52 PM on July 21, 2025: contributor

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33034.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

#bitcoin-core/gui/872 (Menu action to export a watchonly wallet by achow101)
#35018 (wallet, bench: Use Nanobench setup() for wallet benchmarks, and remove DuplicateMockDatabase by achow101)
#34909 (wallet, refactor: modularise wallet by extracting out legacy wallet migration by rkrux)
#34838 (interfaces: typed receive-request APIs by MkDev11)
#34502 (wallet: remove most asserts of WALLET_FLAG_DESCRIPTORS flag by rkrux)
#33033 (wallet, sqlite: Encapsulate SQLite statements in a RAII class by achow101)
#32895 (wallet: Prepare for future upgrades by recording versions of last client to open and decrypt by achow101)
#32763 (wallet: Replace CWalletTx::mapValue and vOrderForm with explicit class members by achow101)
#32489 (wallet: Add exportwatchonlywallet RPC to export a watchonly version of a wallet by achow101)
#27865 (wallet: Track no-longer-spendable TXOs separately by achow101)
#25722 (refactor: Use util::Result class for wallet loading by ryanofsky)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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2026-05-19 21:37:24

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w0xlt commented at 9:15 PM on July 23, 2025: contributor

Concept ACK

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rkrux commented at 8:14 AM on October 9, 2025: contributor

Concept ACK a25557a

I have gone through the PR description and have skimmed over the commit messages as of now. At the outset, I find myself agreeing with the intent here. I am not aware of a strong enough reason to keep using SQLite as a KVS for all purposes, using its relational database properties for wallet transactions seem like a good start. I did notice some serialisation specifics of transaction properties in a couple previous PRs that I didn't fully understand why were required; it could be a lot cleaner and explicit in implementation if using SQLite as an RDBMS can avoid the need for doing those specific serialisations.

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sedited referenced this in commit db98e357d3 on May 2, 2026

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wallet: Pass replaces_txid to CommitTransaction outside of mapValue

Instead of updating mapValue with the "replaces_txid" value and passing
the updated mapValue to CommitTransaction, pass the replaces_txid
directly to CommitTransaction which updates mapValue as necessary.

This is prepration for removing mapValue.

133a284577

wallet: Pass comment and comment_to to CommitTransaction

Instead of passing these by setting them in mapValue, pass them directly
to CommitTransaction.

This is preparation for removing mapValue.

40864c6041

wallet: Drop mapValue from CommitTransaction

The values previously passed in mapValue are now parameters to
CommitTransaction so there is no need for mapValue to be passed.

e7f7670542

wallet: Make CWalletTx "from" and "message" member variables

Instead of storing "from" and "message" inside of mapValue, store these
explicitly as members of CWalletTx.

8eec6a74b2

wallet: Make CWalletTx "comment" and "to" member variables

Instead of storing "comment" and "to" inside of mapValue, store these
expliclty as members of CWalletTx.

8e2ce71a10

wallet: Make CWalletTx "replaces_txid" and "replaced_by_txid" member variables

Instead of storing "replaces_txid" and "replaced_by_txid" as strings inside of
mapValue, store these expliclty as members of CWalletTx.

a1b60b44f8

wallet: Drop mapValue from CWalletTx

It doesn't make sense to be storing relevant metadata variables inside
of a string map in CWalletTx. All of the fields have been pulled out
into separate members, so there is no need for mapValue to stick around.

21c9a7743a

wallet: Drop vOrderForm from CommitTransaction

This parameter is only used to pass in the "Messages" from the GUI.
Instead of making it opaque by putting those into vOrderForm, use a
specific dedicated parameter for providing the messages.

b815b453ab

wallet: Replace CWalletTx's vOrderForm with specific fields

vOrderForm contained 2 kinds of strings: BIP 21 messages, and BIP 70
Payment Requests. Instead of having both inside of a single vOrderForm
field that is opaque, split them into separate std::vector<std::string>
to contain this metadata.

12d5ad6dce

walletdb: Decouple last client record from CLIENT_VERSION

Instead of tying the last client record with the node version, introduce
a separate wallet client version that will be increased as necessary
when new automatic upgrades are introduced.

1827b7c8e7

wallet: Introduce LastClientFeatures flags and LAST_OPENED_FEATURES record

LastClientFeatures are feature flags indicating what automatic upgrade
features supported by the last client that opened the wallet.

The LAST_OPENED_FEATURES record stores these flags and must be
set to match the exact features supported by the client that opens a
wallet.

ab30886e2c

wallet: Record the supported features of the last client to decrypt a wallet 680c4a4ec9

wallet: Set last opened and decrypted features during migration

Set these flags to avoid the automatic upgrade after migrating.

8461ca51ef

sqlite: Add SQLiteStatement RAII class

This class will be used to encapsulate a sqlite3_stmt

836554a93c

sqlite: Make Column template function a92c55a5b4

sqlite: Refactor ReadPragmaInteger to use SQLiteStatement acd94780c6

sqlite: Use SQLiteStatement in PRAGMA integrity_check 418f85a5f5

sqlite: Use SQLiteStatement in check_main_stmt 7d26411138

sqlite: Have SQLiteCursor store SQLiteStatement 3b21b26d07

sqlite: Replace remaining sqlite3_stmt usage with SQLiteStatement 0f8ce4b86e

sqlite: Refactor common writing code from WriteKey and ExecStatement

WriteKey and ExecStatement use the same code for the actual execution of
the statement. This is refactored into a separate function, also called
ExecStatement, and the original ExecStatement renamed to
ExecEraseStatement as it is only used by the erase functions.

e7b04020be

sqlite: Inline BindBlobToStatement and SpanFromBlob eeaa6640c8

sqlite: Construct SQLiteStatements when needed

Instead of constructing all SQLiteStatements when SQLiteBatch is
constructed, construct them once when they are needed before each read,
write, or erase operation. Once constructed, the statement will persist
for the lifetime of the SQLiteBatch to be reused across multiple
statements.

5bd0ca1c01

util: Add span constructor to (W)Txid a6824ab542

sqlite: Make SQLiteStatement::Bind a template function

We will need to bind data types other than blob

e4e212de35

sqlite: Make SQLiteDatabase::Column an std::optional

To handle columns containing NULL values, Column needs to return some
value representing NULL, so make it a std::optional.

d95224e2d8

sqlite: Add additional blob types to SQLiteStatement::Column

Not all blob data types fit in ColumnBlob, so we need additional
template type requirements to match those.

6689b0a13b

wallet: Add Un/Serialize to TxState structs 6442ef139c

wallet: Add new serialization format functions for TxState c3587b777c

sqlite: Create a 'transactions' table if it does not exist 0c1396f5d4

sqlite: Add functions and statements for transactions table c19dc5bbb2

sqlite: Iterate the transactions table with SQLiteCursor 5ef9a67803

walletdb: Add functions to modify transactions table a58411bff6

wallet: Also write to the new transactions table efde59bd4d

wallet: Perform automatic upgrade to using the transactions table 9ea177df06

walletdb: Load from transactions table and use original tx for upgrade

When loading a wallet, always load from the transactions table, except
when loading a legacy wallet for migration.

The original 'tx' records are only used to upgrade to the transactions
table if an upgraded is necessary.

7d6de1124e

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