Documentation
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Overview ¶
Package tablejsonl inspects a JSON-lines file before a table is registered over it, and reads the columns that table declares (#1820). It knows nothing about registrations; tableregister asks it and acts on the answer, as it asks tablecsv about a CSV.
A JSON-lines table is read by Trino's Hive JSON reader, one object per line, and it is the format a table reads back exactly: every string a JSON string can hold, line breaks included, and a null that stays a null. What the reader cannot read is the shape of a line, not the text inside it, and it fails in one of two ways. Most defects fail every query on the table, which is loud but leaves a registration nobody can use. One is silent: a second object on the same line is dropped. Each was observed on Trino 453, and each is refused here, by line, before the DDL runs.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrNoRecords = errors.New("the file holds no records, so there are no columns to declare; " +
"a JSON-lines file names its columns only in its records")
ErrNoRecords means the file holds no record to take a column from. A table declares at least one column, and a JSON-lines file carries its columns only in its records.
Functions ¶
func Columns ¶
Columns reads a JSON-lines file and returns the columns a table over it declares: every key any record carries, lowercased, in the order they are first seen. It refuses a file the reader would fail on or read wrongly, naming the line.
The names are the keys, lowercased and otherwise untouched, because the reader finds a value by matching its key to a column name without regard to case. A CSV column can be renamed (tablecsv.ColumnsFrom fills a blank one and drops a comma) because a CSV is read by position; a key renamed here would be a column the reader never fills.
Types ¶
This section is empty.
Source Files