Work with tables

Go to Data and open Nexus Lakehouse. The list shows each table's Name, Schema and number of Columns; type in Find a table to narrow it. A table's page has three tabs: Data, Columns and History.

The menu beside a table also offers Query in SQL editor or copying its name.

from klarety import Nexus

with Nexus.connect() as nx:
    for table in nx.tables.list("default", search="order"):
        print(table)

    about = nx.tables.describe("orders", schema="default")
    print(about)

tables.list() reads every page of results. made_by="org" keeps the tables made outside any project, and made_by="system" the ones Klarety keeps.

The Data tab shows the rows. A large table shows only its first rows, and says so.

Select Filter rows, pick a Column, a Condition and a Value, then Apply. The conditions are is, is not, contains, more than, less than, is empty and is not empty. Each filter is a removable chip; Clear removes them all.

tables.rows() reads every row, a page at a time. Each filter is written column:op:value:

from klarety import Nexus

with Nexus.connect() as nx:
    for row in nx.tables.rows(
        "orders",
        where=["country:eq:CO"],
        order_by="ordered_at",
        descending=True,
    ):
        print(row)

To fetch many rows by key in one read, use in: where=["order_id:in:1,2,3"].

from klarety import Nexus
from klarety.errors import ConflictError

with Nexus.connect() as nx:
    try:
        nx.tables.edit_rows(
            "orders",
            updated=[{"row": {"order_id": 3}, "values": {"amount": "75.00"}}],
            added=[{"order_id": 9, "customer": "Lucía", "country": "CO", "amount": "40.00"}],
            deleted=[{"order_id": 7}],
        )
    except ConflictError as changed:
        print("Someone changed these rows first:", changed)

Values are given as text. One call takes at most 500 changes, all saved together. Each value in row must still match what is stored, or nothing is saved and ConflictError names each changed row: read again, then retry. After a timeout, resend with the same write_id; it is never applied twice.

The Columns tab lists every column with its type. A column that identifies a row is marked key, and Linked tables shows which columns match columns in other tables. Add description writes one line about a column, shown to everyone who reads the table.

nx.tables.set_column_doc("orders", "amount", "Order total in Colombian pesos, tax included")

An empty description clears it.

tables.expect() replaces the table's checks with the list you send. An empty list removes them all.

from klarety import Nexus

with Nexus.connect() as nx:
    nx.tables.expect(
        "orders",
        [
            {"column": "customer", "rule": "not_null"},
            {"column": "amount", "rule": "range", "minimum": 0},
            {"column": "status", "rule": "one_of", "values": ["paid", "refunded"]},
        ],
    )
    print(nx.tables.quality("orders"))

A write that breaks a rule raises TableRuleError, naming the rule. Fix the data rather than resending it unchanged.

The History tab lists every version, newest first: how many rows were added or that rows were updated, the total row count, who made the change (You, A teammate, Studio or An API key) and how it came in (via SDK, via agent, from a Studio or auto import). Select Show older to go further back.

To undo, select Go back to this on a version.

history = nx.tables.snapshots("orders")
authors = nx.tables.authors("orders", days=7)

snapshots() lists the table's versions; authors() shows who added and changed rows, day by day.

Open More and choose Delete table. You can restore it for a while after.

nx.tables.delete("orders_old")
print(nx.tables.deleted())
nx.tables.restore("orders_old")

A deleted table can be restored for as long as your plan keeps deleted items.