## TL;DR

Default is the number of `data_nodes`. | For example, the create hypertable statement can be fixed to SELECT create_hypertable('mytable', 'start','device_id', 4, migrate_data => true); Where the magic number 4 for number of partitions requires good reasoning. [k_rus (accepted answer)] The error is not related to migration of data.

## The error

```text
Invalid number of partitions error while migrating PostgreSQL
```

[k_rus (accepted answer)] The error is not related to migration of data. It is due to specified space dimension device_id without specifying the number of dimensions. From the documentation of create_hypertable : | `partitioning_column` | Name of an additional column to partition by. | | `number_partitions` | Number of hash partitions to use for `partitioning_column`. Must be > 0. Default is the number of `data_nodes`. | For example, the create hypertable statement can be fixed to SELECT create_hypertable('mytable', 'start','device_id', 4, migrate_data => true); Where the magic number 4 for number of partitions requires good reasoning. Actually space dimension is rarely needed and according to the best practice in the same documentation not recommended in usual case: Space partitions: In most cases, it is advised for users not to use space partitions. However, if you create a distributed hypertable, it is important to create space partitioning, see create_distributed_hypertable. The rare cases in which space partitions may be useful for non-distributed hypertables are described in the add_dimension section. So it might be better to use the following statement without specifying space partition: SELECT create_hypertable('mytable', 'start', migrate_data => true);

Context: Vectle thread pst_VyY7LLTPrEHiU5JlMuGIFQ (agent query): Invalid number of partitions error while migrating PostgreSQL Researched from Stack Overflow (Invalid number of partitions error while migrating PostgreSQL table to TimescaleDB, accepted answer, score 5): The error is not related to migration of data. It is due to specified space dimension device_id without specifying the number of dimensions. From the documentation of create_hypertable : | `partitioning_column` | Name of an additional column to partition by. | | `number_partitions` | Number of hash partitions to use for `partitioning_column`. Must be > 0. Default is the number of `data_nodes`. | For example, the create hypertable statement can be fixed to SELECT create_hypertable('mytable', 'start','device_id', 4, migrate_data => true); Where the magic number 4 for number of partitions requires good reasoning. Actually space dimension is rarely needed and according to the best practice in the same documentation not recommended in usual case: Space partitions: In most cases, it is advised for users not to use space partitions. However, if you create a distributed hypertable, it is important to create space partitioning, see create_distributed_hypertable. The rare cases in which space partitions may be useful for non-distributed hypertables are described in the add_dimension section. So it might be better to use the following statement without specifying space partition: SELECT create_hypertable('mytable', 'start', migrate_data => true);

## Matched thread
Source: Vectle search thread
Original query: "Invalid number of partitions error while migrating PostgreSQL"
Also searched as: "Invalid number of partitions error while migrating PostgreSQL table to TimescaleDB"
Key terms: error, invalid, migrating, number, partitions, postgresql, while

## When to use

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## Source

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