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Technical Tips & Tricks

Previously internal product knowledge now available for you to explore!

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samLooker Staff

published in Technical Tips & Tricks

Where can I use ${view_name.SQL_TABLE_NAME}?Knowledge Drop

Last tested: April 2021 Currently this syntax can be used anywhere that accepts valid SQL, INCLUDING the sql_trigger of a datagroup IF the datagroup is being used for a schedule trigger (not rebuilding PDTs). Docs: https://docs.looker.com/data-modeling/learning-lookml/derived-tables#referencing_derived_tables_in_other_derived_tables This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

In what order does the PDT regenerator check trigger values?Knowledge Drop

Last tested: April 2021 The regenerator checks PDT triggers in a completely arbitrary order. The only rule is that if there are table dependencies, then the regenerator will check in order of those dependencies.What's a dependency?If Table A references Table B in its SQL, then we call that a dependency. For example:view: table_A { derived_table { sql: SELECT * FROM ${table_B.SQL_TABLE_NAME} ;; …This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

Will it Stream?Knowledge Drop

Last tested: Dec 2020 Streaming determines whether or not we can export unlimited results. It is basically the notion of serving data in chunks, rather than pulling all of it into memory. The last section of the Row Limits Help Center Article explains more and lays out exactly when we do and do not stream.Quick Points Table calcs never stream. Custom fields always stream. Merged results never stream. Certain databases can't stream, or can't stream with pivots. This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

Can I remove GROUP BY in Looker-generated SQL?Knowledge Drop

Last tested: April 2021 By default, Looker will group by all dimensions selected. The exception to this is if you select the primary key with no measures, and there are no joins in the query that would cause a fanout of the primary key (as defined by the relationship parameters in the joins). Then Looker knows grouping is pointless and does not add a GROUP BY.You can use cancel_grouping_fields (docs) at the explore level to define a list of fields which should also remove the GROUP BY when any of the fields in the list are selected in the explore.If your use case is a little different, and defining a cancel_grouping_fields at the explore level won't help you achieve your goals, please leave feedback for the product team (instructions here)! This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

Why is SQL Runner not showing all of my tables?Knowledge Drop

Last tested: May 2020 SQL Runner only shows the first 500 tables that the Looker database user has permission to within a schema, and it doesn't update very frequently.First click the gear on the left hand side and select "Refresh Schemas and Tables".If that doesn't work, try a simple SELECT * FROM desired_table LIMIT 10. If the table is there, then Looker might just need some time to see the table and update the list.Otherwise, you might get an error giving you more info about the existence of that table and your permissions to it. It's possible that you lack permission to that table, or that you lack sufficient permissions to the databases' internal schema. (These are all database-level permissions that the Looker database user needs.) This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Default Authentication Into LookerKnowledge Drop

Last tested: May 16, 2019 By default, every Looker user is uniquely identified by their email address. In addition to an email address, each user has a password. The default credentials are thus an email/password combination.Password Requirements:By default, passwords in Looker must be a minimum of ten characters long and contain at least one uppercase and one lowercase letter (A, z), one numeric character (0-9), and one special character (such as !, %, @, or #). Looker provides admins with additional control over password requirements for users on their instance, which can be read about here. More on password restrictions here. More information on resetting a password here.Adding / Editing a User:You can set up a new user by clicking Admin > Users to open the Users page. Click Add Users to create new users and assign their roles. Once a user is made, their unique ID within looker will be their Looker User ID, so their email address, first name, and last name can be changed when usi

samLooker Staff

published in Technical Tips & Tricks

What IP Addresses do I need to allowlist on my database or SFTP / custom SMTP server?Knowledge Drop

Last tested: April 2021 For Looker-hosted customers, this doc tells you which IP addresses to allowlist on your database. It also outlines other options for secure database connection.For those hosting your own instance, you should allowlist the IP(s) that your Looker is running on. You'll also want to make sure you have a static IP set up—if it's a dynamic IP, it could change and prevent your allowlisting from getting the correct IP. This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

How long do query slugs/qid and links live?Knowledge Drop

Last tested: April 2021 Queries are permanent in Looker. A Query ID will never be replaced.Similarly, you can count on a hashed explore link or a SQL Runner query slug lasting forever. This content is subject to limited support.

samLooker Staff

published in Technical Tips & Tricks

Default Query LimitsKnowledge Drop

Last tested: April 2021 The query limits are specified in the startup docs, here are a few of them:--per-user-query-limit= 15--scheduler-query-limit=10 There is also a connection level query limit which defaults to 75.When a query limit is hit, Looker queues up the overflowing queries until one of the other queries finish. This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

What Is SAML and how is it used in Looker?Knowledge Drop

Last tested: Jun 21, 2019 What is SAML?SAML, short for Security Assertion Markup Language, is one of several standards for authentication. It is a Single Sign On (SSO) method - which means you can use it to authenticate to several different web services.Several different companies sell SAML as a way to make authentication easier and standardized across a company. Some examples are Okta and OneLogin.HOW DOES SAML WORK?SAML SSO works by transferring the user’s identity from one place (the identity provider) to another (the service provider). This is done through an exchange of digitally signed XML documents over HTTP and SOAP.A generic interactions among various roles involved in SAML standard can be summarised as follows:Generally user profiles and user credentials are stored centrally within a one system, this can be a home grown system or can be IAM solution. When a user try to access a secured page/resource on an application it directs users to the central identity service via the us

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

How do I give an account alternate login credentials?Knowledge Drop

Last tested: Sep 17, 2020 Assume you have an account which has only ever authenticated via LDAP, SAML, or Google Auth. In order to give it email credentials, so that you can utilise Alternate Login, you'll need to follow these steps:1. Make sure that the account has either the Admin role or has a role that has the "login_special_email" permission.2. Log into the API with an Admin account.3. Use the "create_user_credentials_email" endpoint by giving it the ID of the account (the one you'd like to give an alternate login) and the email in the body: { "email": "example_name@example_email.com" } 4. Now, go back to your Users tab in your Admin section and find the account you'd like to give an alternate login. Click on "Edit". From there, click on the "Send reset link" button.5. Copy the reset link, and make sure you open it in incognito (this prevents your regular credentials from carrying over). Clicking on that link will prompt you to set a First Name and Last Name (which don't really ma

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

[Google Auth] How do I Merge Existing User Accounts when Making a Domain change?Knowledge Drop

Last tested: Aug 6, 2020 Scenario:You currently has Google Authentication enabled on you instance and is changing email domains. You also wants to merge existing users accounts with your new Google Authentication email when they log in to be able to access their content, etc.Steps:Update user addresses on your user accounts to reflect the updated email address with the new domain name Remove the old email address that was used as the Google Authentication credential by utilising the API Endpoint delete_google_auth_credential Login with Google Auth and the accounts will merge, under the new domainMake sure that the Merge by Email option is checked in the Google Authentication page in the Admin Panel, and strongly encourage you to run through the above steps with a test user to ensure it is working as expected.Google Authentication Doc ref Note: A colleague made an extension to help with this:https://github.com/davidtamaki/admin_power_packPlease note this is not officially supported reso

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

What is a SAML NameID and what happens if it changes?Knowledge Drop

Last tested: May 5, 2020 'NameID' it is the IdP's way of indicating a unique id to use for the given user who is logging in. IdPs are free to use whatever value they choose. If you base this on some value that never changes (like and employee id or the like) then all is well. If you base it on something that does change (like an email domain) then you are flirting with us not recognising that this person logging in is the same person as logged in previously (and for which we have tie metadata in the application). If at login time we don't have a user with the given NameID value then we start over and do whatever we do with new users and would not handle a "merge by email" as one would normally expect.If you run into an issue where NameIDs change you need to go through a process of, using the API, deleting SAML credentials, creating email credentials to match the SAML email attribute, killing existing sessions and forcing users to re-login with "merge by email" enabled.You can use the c

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Authorization vs Authentication in LookerKnowledge Drop

Last tested: Aug 15, 2020 In General: At its simplest, Authentication means confirming your own identity, whereas authorization means being allowed access to a system. In other words: authentication is the process of verifying oneself, while authorization is the process of verifying what you have access to.Authentication: enter some information, which is checked against records and verifies your identity Authorization: AFTER your identity is successfully authenticated, your access to certain content is checked (aka the system checks if you are authorized to view certain content)Source / Additional ReadingIn Looker:In the context of Looker's 'auth' methods, the breakdown is as follows:Authentication methods: 2FA, SAML, username/password (default) Authorization AND Authentication methods: LDAP, OIDC, Google OAuth**SAML doesn't explicitly do authorization, though it can have user attributes that looker takes and uses to authorize the user on our end. More about that here**As we discusse

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Can I automatically start Looker on system reboot?Knowledge Drop

Last tested: Jan 21, 2019 Yes!If you use a System5 style startup system the script is looker_init and it is here... https://github.com/looker/customer-scripts/tree/master/startup_scriptsIf you use systemd startups then here is the answer https://github.com/looker/customer-scripts/tree/master/startup_scripts/systemdAnd if cron is running on the system one could always use the crontab file to restart looker https://www.cyberciti.biz/faq/linux-execute-cron-job-after-system-reboot/This post applies if you host your own instance - Looker-hosted instances automatically start on reboot. This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

What is LDAP and how is it used in Looker?Knowledge Drop

Last tested: Jun 21, 2019 LDAP is a protocol for querying a directory. Usually the directory is in AD (Active Directory) form. One of LDAP's many possible functions is to authorise and authenticate users to applications like Looker.HOW DOES LDAP WORK?An AD stores information represented as trees of entries similar to a file system. An LDAP entry is a collection of information about an entity. Each entry consists of three primary components: a distinguished name (DN), a collection of attributes, and a collection of object classes.Distinguished Name (DN): An entry’s distinguished name (DN) uniquely identifies that entry and its position in the directory information tree (DIT) hierarchy. The DN of an LDAP entry is much like the path to a file on a filesystem. An LDAP DN is comprised of zero or more elements called relative distinguished names (RDNs). Each RDN is comprised of one or more (usually just one) attribute-value pairs. For example, “uid=john.doe” represents an RDN comprised of an

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

How does the PDT stable view publish (publish_as_db_view) work?Knowledge Drop

Last tested: Apr 7, 2020 As soon as a PDT build finishes, regardless of the source, a publish task gets enqueued for that PDT, assumingit has the publish as db View flag It is a prod PDT (not dev mode)The publish task will drop the view if it exists and then create it. This is because the PDT name will change. It will do an insert to the pdt_event_log table for use by system_activity for the 'drop view'. How do you check if it worked?Look for the "action" field in system activity's PDT Log exploreGenerated sql will use the pdt hash not stable name, so don't check there! This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Advanced LookML - Hub and Spoke modelingKnowledge Drop

Last tested: Dec 18, 2019 One of the core benefits of LookML is that it stops you from repeating yourself when doing data analysis. Whereas previously you may have saved snippets of SQL queries, bits of business logic you knew you might need again, this process can be error-prone and in a big organization, this doesn’t scale well. With LookML, you write down those snippets just once into universal and reusable query components that are easier to manage. In computer science, this concept is called D.R.Y., or Don’t Repeat Yourself, and it can save you a lot of time (and tears). The mantra is to write the code ahead of time, not every time.What?In large enterprises, the deployment of Looker can grow to a size where the core data team can no longer manage every department’s data needs, and some level of delegation must happen. Splitting up projects so that each department can manage their own becomes advantageous, but how do you maintain consistency?In the hub and spokes architecture, a ce

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Git promotion using a Single Looker environmentKnowledge Drop

Last tested: Jan 28, 2020 Some users are, for one reason or another, limited to using a single Looker instance for dev > prod but have the need for set up a promotion workflow to do testing against different database environments or different application environments. While we recommend setting up additional Looker instances to support this type of workflow, it is possible to set up a dev workflow within a single Looker instance. These are our recommendations for setting up this workflow within a single Looker instance.Assuming we have 3 database environments to test against, set up 3 connections (one for each database) in Admin > Connections. Create a separate git repository for each combination of your Project + workflow step. In example above, we would have 3 Projects and 3 git repos. During git promotion, use git script to update connection parameter and model names. Looker does not allow you to use the same model name more than once in the same Looker instance. See link for

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Can a Looker user submit a pull request without a remote git account/login?Knowledge Drop

Last tested: Jan 21, 2019 No, in order to submit a pull request via the Looker UI, that user must have their own remote git account.More context: We built a git development environment that separates commits by Looker users. We haven't built out pull requests for this environment, so we use the implementation of the Git service (ie Github), which means you need login credentials to that service. This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

Are pull request comments viewable in Looker?Knowledge Drop

Last tested: May 20, 2019 TLDR: No.BackgroundIn most repositories, after a user opens a pull request for a code change, another person reviews the proposed code. The reviewer can either, Approve, Comment, or ask for additional information, prior to merging the pull request. The question is, can these comments or requests be seen in Looker?AnswerNo. All that is seen in Looker is the fact that the pull request has been approved. Comments and requests around pull requests are handled entirely in the UI of the Git provider. This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

BIGQUERY (HowTo): Can Looker query across different BigQuery projects?Knowledge Drop

Last tested: Oct 23, 2018 Yes! All data in BigQuery is universally addressable. The full address of any table in BQ is projectname.datasetname.tablename and queries can join tables from different datasets and even different projects without a problem.However, this can only happen if the account running the query has permission to query both tables. Since Looker generally connects to BQ via a service account, you need to confirm that the service account in Looker's connection has access to all the data you're trying to access. If it doesn't, you'll get a permission denied error. This content is subject to limited support.

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

DATABASE (Concept): Database structures: OLTP vs OLAPKnowledge Drop

Last tested: Aug 28, 2018 OLTP and OLAP are 2 different ways of structuring your database for analysis, each with its own unique strengths and weaknesses.OLTPOLTP stands for On-Line Transactional Processing. It’s used to run fundamental business tasks by enabling fast query processing through maintaining data integrity in its environment. OLTP databases typically have the most detailed and current operational data and is highly normalized with many tables (3NF).Settings where OLTP databases excel include retail, restaurants, commerce, where transactions occur rapidly and the end user (ie. business user) is making relatively short, standardized queries with the purpose of running ongoing business processes. Effectiveness of OLTP databases are measured by transactions per second. OLAPOLAP stands for On-Line Analytical Processing. This type of database is used for planning, problem solving, decision support through the use of historic or archival data. Typically this involves relatively

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

BIGQUERY (Concept): BigQuery ClusteringKnowledge Drop

Last tested: Oct 23, 2018 In August of 2018, Google introduced a beta feature called "Clustering," which allows you to organize, or sort, the contents of your tables by one or more columns. This optimizes performance when filtering or aggregating by those columns. This allows you to optimize performance on a string, because the partitioning can only be done on dates.When to use clustering (for user managing tables in BQ)Currently, BigQuery supports clustering over a partitioned table. Use clustering over a partitioned table when:Your data is already partitioned on a date or timestamp column. You commonly use filters or aggregation against particular columns in your queries.Using with PDTsThere are some downsides that come with clustering discussed in this blog, because the data is only clustered or sorted at the time of the table creation. This means any new data coming into the table will not be sorted or clustered. However, because PDTs need to be consistently rebuilt this does not a

Department of Customer LoveLooker Staff

published in Technical Tips & Tricks

413 Request Entity Too Large ErrorKnowledge Drop

Last tested: Jan 21, 2019 This error can be returned by the proxy that sits in front of the Looker server.This seems to be controlled by the client_max_body_size on the proxy side, documented here:http://nginx.org/en/docs/http/ngx_http_core_module.html#client_max_body_sizeThe default is set to 1M but we set it to 100M on our proxies for our hosted Lookers. This content is subject to limited support.

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