ZRANGEBYLEX for lexicographic queries in Redis - Step-by-Step Execution

Concept Flow - ZRANGEBYLEX for lexicographic queries

Start with Sorted Set

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Define Lex Range: min, max

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ZRANGEBYLEX command runs

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Filter members by lex order

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Return members in lex order

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End

ZRANGEBYLEX filters sorted set members by their lexicographic order within a specified range and returns them.

Execution Sample

Redis

ZADD fruits 0 apple 0 banana 0 cherry 0 date 0 fig
ZRANGEBYLEX fruits [banana [date

Add fruits to a sorted set and get members from 'banana' to 'date' lexicographically.

Execution Table

Step	Action	Lex Range	Members Checked	Members Returned
1	Add members to sorted set	-	-	apple, banana, cherry, date, fig
2	Run ZRANGEBYLEX with range [banana to [date	[banana, date]	apple, banana, cherry, date, fig	banana, cherry, date
3	Return result	-	-	banana, cherry, date

💡 All members checked; only those within lex range returned.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
Sorted Set 'fruits'	empty	apple, banana, cherry, date, fig	apple, banana, cherry, date, fig	apple, banana, cherry, date, fig
Lex Range	undefined	undefined	[banana, date]	[banana, date]
Result	empty	empty	banana, cherry, date	banana, cherry, date

Key Moments - 3 Insights

Why does 'apple' not appear in the result even though it is in the set?

Because 'apple' is lexicographically before the minimum range '[banana' as shown in execution_table row 2, so it is excluded.

What does the '[' symbol mean in the lex range '[banana'?

It means the range includes 'banana' itself (inclusive). This is why 'banana' is included in the result in execution_table row 2.

Why is 'fig' not included in the result?

'fig' is lexicographically after the maximum range '[date', so it is excluded as shown in execution_table row 2.

Visual Quiz - 3 Questions

Look at the execution_table, which members are returned at step 2?

A banana, cherry, date

B apple, banana, cherry

C apple, date, fig

D cherry, date, fig

💡 Hint

Check the 'Members Returned' column in execution_table row 2.

At which step is the lex range defined?

A Step 1

B Step 3

C Step 2

D Lex range is never defined

💡 Hint

Look at the 'Lex Range' column in execution_table and variable_tracker.

If the lex range was changed to (banana [date, which member would be excluded?

A date

B banana

C cherry

D apple

💡 Hint

The '(' means exclusive, so check which member matches the lower bound in variable_tracker.

Concept Snapshot

ZRANGEBYLEX key min max
- Returns members in sorted set by lex order
- min and max define lex range
- Use '[' for inclusive, '(' for exclusive
- Members outside range are excluded
- Scores are ignored, only lex order matters

Full Transcript

ZRANGEBYLEX is a Redis command that returns members of a sorted set within a lexicographic range. First, members are added to the sorted set with ZADD. Then, ZRANGEBYLEX is called with a minimum and maximum lex range, using '[' for inclusive and '(' for exclusive bounds. The command checks each member's lex order and returns only those within the range. For example, with members apple, banana, cherry, date, fig, and range [banana to [date, the result is banana, cherry, date. Members outside the range like apple and fig are excluded. This command ignores scores and filters purely by lexicographic order.