Tableau Interview Questions in Bangalore

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A bin is a dimension created from a continuous measure by splitting values into equal-sized ranges, for example ages in buckets of 10. A histogram is the chart that counts records in each bin. Tableau can create both automatically through Show Me. You can choose bin size manually or tie it to a parameter so users change bucket width interactively.

Users say the dashboard takes 30 seconds to load on Server but is fast in Desktop. What do you check?

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Compare data connection, since Server may use a live connection through a slower network or different credentials. Record performance on Server using the performance recording parameter. Check concurrent load, VizQL and cache settings, the number of quick filters and marks, and whether extracts are refreshing at the same time. Ask the Server admin for resource usage and background job schedules.

When would you choose an LOD over a table calculation?

Table CalculationsHard

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Choose an LOD when the result must be used as a dimension, a filter, in another data source level calculation, or must stay correct regardless of view layout, such as a customer's first purchase. Choose a table calculation for sequence-based logic such as running totals, ranks, moving averages and previous period values. LODs run in the database; table calcs run locally on the result set.

How do you create a navigation menu between multiple dashboards?

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Add Navigation objects or buttons from the Objects pane, set each to go to a target dashboard, and style them with text or images. Place them in a horizontal container at the top of each dashboard for consistency. Use Go to Sheet actions for drill-through from charts. Hide sheets and use Show Sheets as Tabs off when publishing, so users rely on the custom menu.

How do you improve dashboard performance in Tableau?

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Use the performance recorder to find slow queries and rendering. Use extracts with only needed fields and rows, aggregate data, reduce marks and sheets, limit quick filters and relevant values, prefer integer and boolean calculations, avoid heavy custom SQL, use fixed dashboard size for caching, and hide unused fields. Workbook Optimizer in Desktop also suggests improvements based on best practices.

How do you create a donut chart in Tableau?

Charts and Visual DesignMedium

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Create a pie on the first axis using a measure on Angle and a dimension on Color. Put two copies of MIN(0) on Rows, set the second to circle mark, make it smaller and white, and select Dual Axis with synchronised axes. Place a total label on the inner circle. Use donuts only for two to four segments; bar charts are usually clearer.

A business user wants a chart where they can switch between Sales, Profit and Quantity. How would you build it?

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Create a string parameter with the values Sales, Profit and Quantity. Create a calculated field: CASE [Measure Selector] WHEN 'Sales' THEN SUM([Sales]) WHEN 'Profit' THEN SUM([Profit]) ELSE SUM([Quantity]) END. Use this field on the axis, show the parameter control, and put the parameter in the title so users know which measure they see. Number formatting can be handled with separate calculations if needed.

What is a union and when do you use it?

Data Connections and ModellingMedium

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A union stacks tables with the same structure on top of each other, adding rows rather than columns. It is used for monthly or regional files such as Sales_Jan, Sales_Feb and Sales_Mar. Tableau supports manual unions and wildcard unions that pick up files or sheets matching a name pattern, and adds Table Name and Path fields to identify the source of each row.

An extract refresh fails every morning on Server. How do you troubleshoot?

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Check the background task and job history for the error message. Common causes are expired or changed database passwords, firewall or VPN issues, schema changes like renamed columns, timeout because the query is too large, or Backgrounder overload at peak time. Fix credentials, update the data source, optimise the query or move the schedule. Set up failure email notifications.

Describe how you work with data engineers on a BI project.

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Situation: my dashboard needed customer data that was spread across three systems. Task: get a reliable, single table. Action: I wrote clear requirements with grain, fields and refresh needs, shared sample SQL, and reviewed their view together, testing counts against source systems. Result: they built a curated table, my dashboard became simpler and faster, and we reused the table for two other reports.

What are device layouts in Tableau dashboards?

Dashboards and Tableau ServerEasy

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Device layouts let you design separate versions of a dashboard for desktop, tablet and phone within the same dashboard. You can add, remove and rearrange items for each device, and Tableau shows the right layout based on screen size. For Indian field sales teams who check dashboards on mobile, a phone layout with key KPIs stacked vertically is very useful.

How would you set up row-level security using a user entitlement table?

Dashboards and Tableau ServerHard

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Create an entitlement table with Username and Region columns, maintained by the business or IT. Relate or join it to the fact table on Region. Create a calculation USERNAME() = [Username] and add it as a data source filter set to True. Publish the data source with embedded credentials and restrict download permissions. Test with View As or user impersonation for each role.

How do you create a filter action from a map to other sheets?

Filters, Parameters and ActionsMedium

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Go to Dashboard, Actions, Add Action, Filter. Choose the map as source sheet, select the target sheets, set run on Select, and choose what happens when clearing the selection, such as Show all values. Under Filter, choose Selected Fields and map State to State. Test by clicking a state and checking that the bar and trend charts update.

What is the difference between dimensions and measures in Tableau?

Tableau FundamentalsEasy

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Dimensions are qualitative fields such as Region, Product or Order Date that slice data and create headers. Measures are quantitative fields such as Sales or Profit that Tableau aggregates, usually with SUM by default. Dragging a dimension adds detail or categories to the view, while a measure produces an axis. A numeric field like Employee ID can be converted to a dimension when it should not be summed.

Are LOD expressions dimensions or measures?

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FIXED LODs with dimensions return row-level values that can be used as dimensions, for example a customer's first order year used for cohort analysis. Tableau puts them in measures by default when the result is numeric, but you can convert them to dimension. INCLUDE and EXCLUDE results are measures because they depend on the view. Converting FIXED to a dimension is common for bucketing.

An interviewer asks you to find the highest-selling product in each category. How do you approach it?

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Calculate category max: {FIXED [Category] : MAX({FIXED [Category], [Product Name] : SUM([Sales])})}. Then flag: IF {FIXED [Category], [Product Name] : SUM([Sales])} = [Category Max] THEN 'Top' END and filter to Top. A simpler alternative is a RANK table calculation computed along products within each category, filtering rank equal to 1.

What is the Tableau order of operations?

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Tableau applies filters and calculations in a fixed sequence: extract filters, data source filters, context filters, then sets, Top N and FIXED LOD, then dimension filters, then INCLUDE and EXCLUDE LOD and blending, then measure filters, then table calculations, totals and reference lines, and finally table calculation filters and trend lines. Knowing this explains why a FIXED calculation ignores a normal dimension filter unless it is added to context.

Top 10 products do not change when the user selects a region. Why?

Filters, Parameters and ActionsEasy

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Top N filters run before normal dimension filters, so Top 10 is computed on all regions, and then the region filter removes some of those products. Add the Region filter to context, so it runs first and Top 10 is calculated within the selected region. The Region pill turns grey to show it is a context filter.

Using FIXED with SUM in the view gives a huge inflated number. Why?

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FIXED returns a value repeated on every row at the fixed level. If the view is at a finer level, or at the total level, SUM adds the repeated values, multiplying the result. Use MIN, MAX or AVG to bring back the single value, or make sure the view level matches the FIXED dimensions. This is a frequent mistake when using table-level totals.

What are relative date filters?

Filters, Parameters and ActionsEasy

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Relative date filters show data relative to today or an anchor date, such as last 7 days, this month, previous quarter, or year to date. They update automatically each day, so dashboards always show current periods without manual editing. You can set an anchor date for testing or use a parameter, and choose whether to include null dates.

What does {FIXED : SUM([Sales])} return?

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With no dimension, FIXED computes at the table level, returning grand total sales for the whole data source, after context and data source filters. It is useful for percent of total: SUM([Sales]) / MIN({FIXED : SUM([Sales])}). Since it repeats on every row, wrap it in MIN, MAX or AVG in the view rather than SUM, which would multiply the total.

Users complain that a dashboard with 10 dropdown filters is slow. How do you improve it?

Filters, Parameters and ActionsMedium

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Measure first with performance recording. Reduce the number of quick filters and replace some with dashboard filter actions. Change Only Relevant Values to All Values in Database where cascading is not needed. Add an Apply button to multi-select filters, convert high-cardinality filters to wildcard search, and move fixed restrictions to data source filters. Re-test after changes.

What is the difference between a heat map, highlight table and treemap?

Charts and Visual DesignEasy

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A highlight table is a text table with cells coloured by a measure, good for showing exact values with patterns. A heat map uses square marks sized or coloured to show density across two dimensions. A treemap shows hierarchical part-to-whole data as nested rectangles sized by one measure and coloured by another. Treemaps suit many categories but make precise comparison harder.

What are the main categories of functions in Tableau calculations?

Calculated FieldsEasy

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Tableau offers number functions such as ROUND and ABS, string functions such as LEFT, CONTAINS and SPLIT, date functions such as DATEDIFF, DATEADD and DATETRUNC, type conversion such as STR, INT and DATE, logical functions such as IF, CASE and IIF, aggregate functions such as SUM and COUNTD, user functions such as USERNAME, and table calculation functions such as RUNNING_SUM and RANK.

Create age buckets for customers using a calculation.

Calculated FieldsMedium

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Age Group: IF [Age] < 18 THEN 'Under 18' ELSEIF [Age] <= 25 THEN '18-25' ELSEIF [Age] <= 35 THEN '26-35' ELSEIF [Age] <= 50 THEN '36-50' ELSE '50+' END To sort buckets correctly, create a sort order calculation or sort manually.

How does forecasting work in Tableau?

Charts and Visual DesignMedium

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Tableau uses exponential smoothing models to forecast continuous time series. It chooses the best model, with or without trend and seasonality, based on the data and shows prediction intervals. You need a continuous date and a measure. Options include forecast length, aggregation level and ignoring the last incomplete period. It suits quick projections, while complex forecasting needs Python or R integration.

What do addressing and partitioning mean in table calculations?

Table CalculationsMedium

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Addressing fields define the direction the calculation moves along, such as across months. Partitioning fields define the groups where the calculation restarts, such as each region. In Compute Using, checked dimensions are addressing and unchecked ones are partitioning. For a running total of sales by month restarting each year, month is addressing and year is partitioning.

What are the important date functions in Tableau?

Calculated FieldsMedium

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DATEPART returns an integer part of a date such as month number. DATENAME returns the name, such as March. DATETRUNC truncates to a level, giving a date such as the first of the month. DATEADD adds intervals, DATEDIFF computes the difference between two dates in a unit, MAKEDATE builds a date, and TODAY and NOW return the current date and time.

What is meant by granularity or level of detail of a view?

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The level of detail of a view is the combination of dimensions placed on Rows, Columns and the Marks card. Each unique combination produces one mark. If only Region is in the view, Sales is summed per region; adding Category on Detail splits each region into category marks. Understanding view granularity is the foundation for LOD expressions and for explaining why numbers change when fields are added.

What are reference lines, bands and distributions?

Charts and Visual DesignMedium

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Reference lines mark a constant, average, median or parameter value across an axis, such as a target. Reference bands shade a range between two values, such as acceptable delivery time. Distributions show percentiles, quantiles or standard deviations. They are added from the Analytics pane or by right-clicking an axis, and can be computed per table, pane or cell.

How do you build a dynamic Top 10 customers chart?