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full paths, add users_file_dir

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DanRoscigno 2022-12-29 21:53:42 -05:00
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docs/en/operations/system-tables/schema_inference_cache.md
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@ -6,30 +6,38 @@ slug: /en/operations/system-tables/schema_inference_cache
Contains information about all cached file schemas.
Columns:
- `storage` ([String](../../sql-reference/data-types/string.md)) — Storage name: File, URL, S3 or URL.
- `source` ([String](../../sql-reference/data-types/string.md)) — File source.
- `format` ([String](../../sql-reference/data-types/string.md)) — Format name.
- `additional_format_info` ([String](../../sql-reference/data-types/string.md)) - Additional information required to identify the schema. For example, format specific settings.
- `registration_time` ([DateTime](../../sql-reference/data-types/datetime.md)) — Timestamp when schema was added in cache.
- `schema` ([String](../../sql-reference/data-types/string.md)) - Cached schema.
- `storage` ([String](/docs/en/sql-reference/data-types/string.md)) — Storage name: File, URL, S3 or URL.
- `source` ([String](/docs/en/sql-reference/data-types/string.md)) — File source.
- `format` ([String](/docs/en/sql-reference/data-types/string.md)) — Format name.
- `additional_format_info` ([String](/docs/en/sql-reference/data-types/string.md)) - Additional information required to identify the schema. For example, format specific settings.
- `registration_time` ([DateTime](/docs/en/sql-reference/data-types/datetime.md)) — Timestamp when schema was added in cache.
- `schema` ([String](/docs/en/sql-reference/data-types/string.md)) - Cached schema.
**Example**
Let's say we have a file `data.jsonl` with the next content:
Let's say we have a file `data.jsonl` with this content:
```json
{"id" : 1, "age" : 25, "name" : "Josh", "hobbies" : ["football", "cooking", "music"]}
{"id" : 2, "age" : 19, "name" : "Alan", "hobbies" : ["tennis", "art"]}
{"id" : 3, "age" : 32, "name" : "Lana", "hobbies" : ["fintess", "reading", "shopping"]}
{"id" : 3, "age" : 32, "name" : "Lana", "hobbies" : ["fitness", "reading", "shopping"]}
{"id" : 4, "age" : 47, "name" : "Brayan", "hobbies" : ["movies", "skydiving"]}
```
Let's run `DESCRIBE` query:
:::tip
Place `data.jsonl` in the `user_files_path` directory. You can find this by looking
in your ClickHouse configuration files. The default is:
```
<user_files_path>/var/lib/clickhouse/user_files/</user_files_path>
```
:::
Open `clickhouse-client` and run the `DESCRIBE` query:
```sql
DESCRIBE file('data.jsonl') SETTINGS input_format_try_infer_integers=0;
```
```text
```response
┌─name────┬─type────────────────────┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┬─ttl_expression─┐
│ id │ Nullable(Float64) │ │ │ │ │ │
│ age │ Nullable(Float64) │ │ │ │ │ │
@ -38,19 +46,25 @@ DESCRIBE file('data.jsonl') SETTINGS input_format_try_infer_integers=0;
└─────────┴─────────────────────────┴──────────────┴────────────────────┴─────────┴──────────────────┴────────────────┘
```
Let's see the content of `system.schema_inference_cache` table:
Let's see the content of the `system.schema_inference_cache` table:
```sql
SELECT * FROM system.schema_inference_cache;
SELECT *
FROM system.schema_inference_cache
FORMAT Vertical
```
```response
Row 1:
──────
storage: File
source: /home/droscigno/user_files/data.jsonl
format: JSONEachRow
additional_format_info: schema_inference_hints=, max_rows_to_read_for_schema_inference=25000, schema_inference_make_columns_nullable=true, try_infer_integers=false, try_infer_dates=true, try_infer_datetimes=true, try_infer_numbers_from_strings=true, read_bools_as_numbers=true, try_infer_objects=false
registration_time: 2022-12-29 17:49:52
schema: id Nullable(Float64), age Nullable(Float64), name Nullable(String), hobbies Array(Nullable(String))
```
```text
┌─storage─┬─source───────────────────────────────────────────────────────────┬─format──────┬─additional_format_info────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───registration_time─┬─schema──────────────────────────────────────────────────────────────────────────────────────────────┐
│ File │ /etc/clickhouse-server/user_files/hobbies.jsonl │ JSONEachRow │ schema_inference_hints=, max_rows_to_read_for_schema_inference=25000, schema_inference_make_columns_nullable=true, try_infer_integers=false, try_infer_dates=true, try_infer_datetimes=true, try_infer_numbers_from_strings=true, read_bools_as_numbers=true, try_infer_objects=false │ 2022-12-23 16:17:24 │ id Nullable(Float64), age Nullable(Float64), name Nullable(String), hobbies Array(Nullable(String)) │
└─────────┴──────────────────────────────────────────────────────────────────┴─────────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴─────────────────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────┘
```
**See also**
- [Automatic schema inference from input data](../../interfaces/schema-inference.md)
- [Automatic schema inference from input data](/docs/en/interfaces/schema-inference.md)
[Original article](https://clickhouse.com/docs/en/operations/system-tables/schema_inference_cache) <!--hide-->