90 lines
2.9 KiB
Markdown
90 lines
2.9 KiB
Markdown
# Indexing Transactions
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Tendermint allows you to index transactions and later query or subscribe
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to their results.
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Let's take a look at the `[tx_index]` config section:
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##### transactions indexer configuration options #####
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[tx_index]
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# What indexer to use for transactions
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#
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# Options:
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# 1) "null" (default)
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# 2) "kv" - the simplest possible indexer, backed by key-value storage (defaults to levelDB; see DBBackend).
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indexer = "kv"
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# Comma-separated list of tags to index (by default the only tag is tx hash)
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#
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# It's recommended to index only a subset of tags due to possible memory
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# bloat. This is, of course, depends on the indexer's DB and the volume of
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# transactions.
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index_tags = ""
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# When set to true, tells indexer to index all tags. Note this may be not
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# desirable (see the comment above). IndexTags has a precedence over
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# IndexAllTags (i.e. when given both, IndexTags will be indexed).
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index_all_tags = false
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By default, Tendermint will index all transactions by their respective
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hashes using an embedded simple indexer. Note, we are planning to add
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more options in the future (e.g., Postgresql indexer).
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## Adding tags
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In your application's `DeliverTx` method, add the `Tags` field with the
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pairs of UTF-8 encoded strings (e.g. "account.owner": "Bob", "balance":
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"100.0", "date": "2018-01-02").
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Example:
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func (app *KVStoreApplication) DeliverTx(tx []byte) types.Result {
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...
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tags := []cmn.KVPair{
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{[]byte("account.name"), []byte("igor")},
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{[]byte("account.address"), []byte("0xdeadbeef")},
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{[]byte("tx.amount"), []byte("7")},
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}
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return types.ResponseDeliverTx{Code: code.CodeTypeOK, Tags: tags}
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}
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If you want Tendermint to only index transactions by "account.name" tag,
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in the config set `tx_index.index_tags="account.name"`. If you to index
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all tags, set `index_all_tags=true`
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Note, there are a few predefined tags:
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- `tm.event` (event type)
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- `tx.hash` (transaction's hash)
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- `tx.height` (height of the block transaction was committed in)
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Tendermint will throw a warning if you try to use any of the above keys.
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## Querying transactions
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You can query the transaction results by calling `/tx_search` RPC
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endpoint:
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curl "localhost:26657/tx_search?query=\"account.name='igor'\"&prove=true"
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Check out [API docs](https://tendermint.github.io/slate/?shell#txsearch)
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for more information on query syntax and other options.
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## Subscribing to transactions
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Clients can subscribe to transactions with the given tags via Websocket
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by providing a query to `/subscribe` RPC endpoint.
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{
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"jsonrpc": "2.0",
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"method": "subscribe",
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"id": "0",
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"params": {
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"query": "account.name='igor'"
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}
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}
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Check out [API docs](https://tendermint.github.io/slate/#subscribe) for
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more information on query syntax and other options.
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