import pyexasol
from exasol.nb_connector.connections import open_pyexasol_connection
from exasol.nb_connector.secret_store import Secrets
# All secret store entries with language container activation commands
# will have this common prefix in their keys.
ACTIVATION_KEY_PREFIX = "language_container_activation_"
def get_registered_languages_string(conf: Secrets) -> str:
"""
Gets the session level language definitions from the database. Returns a string
in a format of a space separated list: "<alias1>=<url1> <alias2=<url2> ..."
"""
with open_pyexasol_connection(conf) as pyexasol_conn:
query_result = pyexasol_conn.execute(
"SELECT SESSION_VALUE FROM SYS.EXA_PARAMETERS WHERE PARAMETER_NAME='SCRIPT_LANGUAGES'"
).fetchall()
return query_result[0][0]
def get_registered_languages(conf: Secrets) -> dict[str, str]:
"""
Collects the existing, session level, language definitions from the database.
Returns them as a dictionary {alias: language_url}
"""
lang_definitions_str = get_registered_languages_string(conf)
result: dict[str, str] = {}
for lang_definition in lang_definitions_str.split():
alias, lang_url = lang_definition.split("=", maxsplit=1)
result[alias] = lang_url
return result
def get_requested_languages(conf: Secrets) -> dict[str, str]:
"""
Collects language definitions from the secret store. Returns them as a
dictionary {alias: language_url}.
Raises a RuntimeError if tt finds two entries with the same alias but
different language definitions (i.e. URLs).
"""
result: dict[str, str] = {}
# Iterate over all entries that look like language definitions.
for key, value in conf.items():
if key.startswith(ACTIVATION_KEY_PREFIX):
alias, lang_url = value.split("=", maxsplit=1)
alias = alias.upper()
if alias in result:
if result[alias] != lang_url:
error = (
"Unable to merge multiple language definitions. "
f"Found incompatible definitions for the language alias {alias}."
)
raise RuntimeError(error)
else:
result[alias] = lang_url
return result
[docs]
def get_activation_sql(conf: Secrets) -> str:
"""
Merges multiple language definitions (i.e. URLs) found in the secret store with
language definitions currently registered in the database at the SESSION level.
Returns a language activation command which combines all that language definitions.
For details on how an activation command may look like please refer to
https://docs.exasol.com/db/latest/database_concepts/udf_scripts/adding_new_packages_script_languages.htm
The secret store entries containing language definitions should have keys with a
common prefix. This prefix is defined in the ACTIVATION_KEY_PREFIX.
Multiple language definitions in the secret store would normally have unique
aliases. In case there are more than one entry with the same alias, their
definitions should match. Otherwise, a RuntimeError will be raised. If a language
with the same aliases is already present in the database, its definition will be
overwritten, no exception raised.
"""
# Collect language definitions, either already registered in the database or
# recorded in the secret store.
lang_definitions = get_registered_languages(conf)
lang_definitions.update(get_requested_languages(conf))
# Build and return an SQL command for the language container activation.
merged_langs_str = " ".join(
f"{key}={value}" for key, value in lang_definitions.items()
)
return f"ALTER SESSION SET SCRIPT_LANGUAGES='{merged_langs_str}';"
[docs]
def open_pyexasol_connection_with_lang_definitions(
conf: Secrets, **kwargs
) -> pyexasol.ExaConnection:
"""
Opens a `pyexasol` connection and applies the `ALTER SESSION` command using all registered languages.
"""
conn = open_pyexasol_connection(conf, **kwargs)
conn.execute(get_activation_sql(conf))
return conn
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