Database Systems (DBMS) 6 demos
How a database stores, finds and plans access to data.
Database Indexing
Why queries are slow: table pages must travel from disk into RAM. Race a full table scan against an index lookup and watch disk reads, RAM checks and time on a live scoreboard.
Hashing
Four modes: a hash table with chaining or open addressing (linear, quadratic, double hashing, rehashing), a static hash index on disk with overflow pages and range queries, extendible hashing with directory doubling, and linear hashing with round-robin splits.
Query Optimizer
Type any SQL query and watch it become a plan: the parser builds the query tree, the rewriter (RBO) applies rules like predicate pushdown, and the planner (CBO) uses statistics and costs to pick access paths, join order and join methods.
Table Joins
Nested loop, index nested loop, hash join and merge join side by side: watch every comparison light up a matrix of all row pairs, and compare the work on a live scoreboard.
Index Types
Clustered vs non-clustered, dense vs sparse, and specialised indexes — bitmap, GIN, GiST and BRIN — each walked through with a query that shows what it skips and what it costs.
Recursive CTE
WITH RECURSIVE built round by round: the anchor runs once, then the recursive part feeds on the working table until nothing new appears. Watch the result grow on an org chart and on flight routes, and see why a cycle needs UNION.
Data Structures & Algorithms 3 demos
Core structures and the classic algorithms that work on them.
B-Tree
Insertion with node splits, deletion with borrowing and merging, and search, animated step by step with pseudocode. Drag keys in and out of the tree.
B+ Tree
All keys in linked leaves: leaf splits copy a key up, internal splits move it, deletes borrow or merge, and range search walks along the leaf chain. Animated step by step with pseudocode.
Sorting Algorithms
Bubble, selection, insertion, merge, quick and heap sort on animated bars: every comparison and swap explained, with counters, pseudocode, merge sort's temp array and heap sort's tree.