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In my data work, I encountered the need for a straightforward way to asynchronously gather small pieces of data into larger batches and efficiently transmit them to Clickhouse.
To address this requirement, I developed the clickcache
package.
сlickcache
excels at working not only with the official clickhouse client but also with third-party clients.
It does so by delegating the read/write work to them while focusing on data aggregation in one central location and preparing it for insertion.
This cache collector will support of is actually supporting caching data
npm install clickcache
const config: ResolverOptions = {
chunkLifeMs: 60000, // Set the time to live limit for chunks
chunkSize: 1000, // Set the max size limit for chunks
checkIntervalMs: 10000, // Set the check interval. It is normal to check batches state 5-10 times per TTL
dataWatcher: 'disk', // Choose the way to store data
disk: {
outputDirectory: './chunks' // Both absolute and relative path work
}
}
// define the singleton resolver instance
const resolver = new ChunkResolver(config)
// set as much handlers as you need
// sync handler to log chunk output
resolver.onResolved(chunk => {
console.log(chunk.id)
console.log(chunk.size)
})
// async handler to pass data in clickhouse storage
resolver.onResolved(async chunk => {
const myRows = await chunk.loadRows()
await clickhouseClient
.insertFunction(chunk.table, myRows)
.then(() => console.log('Hurrah! My data is saved!'))
.catch(e => resolver.cache(chunk.table, myRows))
})
// use this method to cache a few rows or a single row
// it will be stored and collected to a huuuge batch of data
const chunk = await resolver.cache(myTable, rows)
This package contains some enities
ChunkResolver
ChunkRegistry
DataWatcher
Chunk
It collects many single rows by uning ChunkResolver
, then arranges these rows to chunks. When the chunk is ready, ChunkResolver
passes it to your your handlers, where you are able to process database insertion
Chunk
has a relation to ChunkRegistry
and DataWatcher
ChunkRegistry
is a in-memory storage shared within all parts of the core functionality. It contains chunk metadata such as chunk state (is blocked or not, is consistent or not, is expired or not etc) and chunk refs itself
Chunk
has a relation with the stored data though DataWatcher
and can load
it according your need
DataWatcher
is an abstract entity which interacts with the data. Data can be stored in process memory
, disk storage
and cloud
. Data watcher can store and restore your data.
For example, you are using the disk storage
watcher. You are caching your data and someshing goes wrong with the main process. It restarts, restores the last state of data and concistently resolves it
It is not possible to restore the data by using process memory
data watcher