The schema of an Iceberg table

Usage

icebergr_schema(tbl, snapshot_id = NULL)

Arguments

tbl: An icebergr_table from icebergr_table().
snapshot_id: Report the schema as it was at this snapshot rather than the current one. A character id from icebergr_snapshots().

Value

A tibble with one row per top-level field: field_id, name, type (the Iceberg type), required and doc.

Details

Iceberg records a schema per snapshot, so a table whose columns were changed by another engine has more than one. snapshot_id is how the earlier one is read, and it is also what icebergr_scan() resolves filter and select against when it is given a snapshot_id or an as_of: a column that has since been renamed or dropped is still nameable as of the snapshot that had it.

Examples

tbl <- icebergr_example_table(rows = 10)
icebergr_schema(tbl)
#> # A tibble: 5 × 5
#>   field_id name        type        required doc  
#>      <int> <chr>       <chr>       <lgl>    <chr>
#> 1        1 id          int         FALSE    NA   
#> 2        2 event       string      FALSE    NA   
#> 3        3 amount      double      FALSE    NA   
#> 4        4 day         date        FALSE    NA   
#> 5        5 recorded_at timestamptz FALSE    NA   

# The schema as of the first snapshot.
history <- icebergr_snapshots(tbl)
icebergr_schema(tbl, snapshot_id = history$snapshot_id[[1]])
#> # A tibble: 5 × 5
#>   field_id name        type        required doc  
#>      <int> <chr>       <chr>       <lgl>    <chr>
#> 1        1 id          int         FALSE    NA   
#> 2        2 event       string      FALSE    NA   
#> 3        3 amount      double      FALSE    NA   
#> 4        4 day         date        FALSE    NA   
#> 5        5 recorded_at timestamptz FALSE    NA