Lei, HUANG

fix: start datanode instance before frontend services

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I hereby agree to the terms of the [GreptimeDB CLA](https://gist.github.com/xtang/6378857777706e568c1949c7578592cc) ## What's changed and what's your intention? - Break datanode startup process into "start components" and "start services" - When...

Imporve GreptimeDB startup performance

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### What type of enhancement is this? Performance ### What does the enhancement do? When hundreds of tables are created in GreptimeDB, it may take a long time to open...

### What problem does the new feature solve? Shared-data architecture binds dedicated local storage to every computing node, which has good performance for small IO operations like continous insertions. But,...

Table engine supports multi-region

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### What type of enhancement is this? Tech debt reduction ### What does the enhancement do? Currently in GreptimeDB, only one region can be created for a table on one...

Duplicated definition of Values

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### What type of bug is this? Other ### What subsystems are affected? Other ### What happened? Seems there're two identical definitions for `Values` https://github.com/GreptimeTeam/greptimedb/blob/74ea529d1a409551394ad457ce6d571e238c774a/src/storage/proto/write_batch.proto#L67-L85 https://github.com/GreptimeTeam/greptimedb/blob/c1b8981f61873a4b4466184e59901566177ce7e9/src/api/greptime/v1/column.proto#L15-L36 Not sure if it's...

Disambiguatation of existing schemas.

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### What type of enhancement is this? Other ### What does the enhancement do? Looks like there are too many "schemas" in project: - ColumnSchema https://github.com/GreptimeTeam/greptimedb/blob/8959dbcef83507ccd76aaaffd2b44cab6426e68f/src/datatypes/src/schema.rs#L42 - Schema https://github.com/GreptimeTeam/greptimedb/blob/8959dbcef83507ccd76aaaffd2b44cab6426e68f/src/datatypes/src/schema.rs#L138 -...

feat: support multi regions on datanode

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I hereby agree to the terms of the [GreptimeDB CLA](https://gist.github.com/xtang/6378857777706e568c1949c7578592cc) ## What's changed and what's your intention? Support mutliple regions on datanode. ## Checklist - [X] I have written the...

In #456 we've moved SQL parsing stuff to frontend, but some work remains unfinished. As mentioned in [this comment](https://github.com/GreptimeTeam/greptimedb/issues/456#issuecomment-1313006330), both standalone and distributede mode, frontend communicates with datanode thru gRPC...

ndjson inferred schema differs from the schema inferred by JsonFormat when integrate with arrow-datafusion

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# What I'm trying to do AFAIK many open source projects are using datafusion as query engine but they also want to leverage the peformance of arrow2. But the arrow2...

Support `APPROX_COUNT_DISTINCT ` in SQL

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### What problem does the new feature solve? Current `COUNT` operator relies on loading all SST files and deduplicating rows to calculate an accurate row count. That would be unnecessary...