Akshat Aggarwal — BlogsAkshat Aggarwal, Software Engineer 2 at Intuit in Bengaluru working on distributed systems, data platforms, and reliable APIs.https://akshataggarwal.is-a.dev/Postgres Indexes: Why Column Order Mattershttps://akshataggarwal.is-a.dev/blogs/postgres-indexes-why-column-order-matters/https://akshataggarwal.is-a.dev/blogs/postgres-indexes-why-column-order-matters/The same columns can be fast or useless depending on order: B-tree column order in practice.Sun, 01 Feb 2026 00:00:00 GMTPostgreSQLdatabasesA Missing PostgreSQL Indexhttps://akshataggarwal.is-a.dev/blogs/a-missing-postgresql-index/https://akshataggarwal.is-a.dev/blogs/a-missing-postgresql-index/A missing index turned a pre-release test into a production fire, and the zero-downtime fix.Thu, 31 Jul 2025 00:00:00 GMTPostgreSQLdatabasesAuthZ in productionhttps://akshataggarwal.is-a.dev/blogs/authz-in-production/https://akshataggarwal.is-a.dev/blogs/authz-in-production/RBAC vs ABAC, policy-as-code, and OPA: how authorization works in production systems.Thu, 31 Jul 2025 00:00:00 GMTSecuritysecurityUsing PostgreSQL CTEshttps://akshataggarwal.is-a.dev/blogs/using-postgresql-ctes/https://akshataggarwal.is-a.dev/blogs/using-postgresql-ctes/A practical guide to writing readable, correct queries with PostgreSQL common table expressions.Tue, 29 Apr 2025 00:00:00 GMTPostgreSQLdatabasesHow do you win at Nim?https://akshataggarwal.is-a.dev/blogs/nim-game-notes/https://akshataggarwal.is-a.dev/blogs/nim-game-notes/From one pile to three: winning and losing positions, and the xor rule that decides them all.Wed, 19 Jul 2023 00:00:00 GMTCPdsaHow does Mo's algorithm answer range queries?https://akshataggarwal.is-a.dev/blogs/mos-algorithm-notes/https://akshataggarwal.is-a.dev/blogs/mos-algorithm-notes/Offline sqrt decomposition for range queries: complexity analysis, the odd-even trick, and Mo's with updates.Sun, 02 Apr 2023 00:00:00 GMTCPdsaWhat is a trie, and why use one?https://akshataggarwal.is-a.dev/blogs/trie-notes/https://akshataggarwal.is-a.dev/blogs/trie-notes/Prefix trees for autocomplete, spellcheck, and xor queries — structure, tradeoffs, and Codeforces problems.Sat, 16 Jul 2022 00:00:00 GMTCPdsaHow does centroid decomposition work?https://akshataggarwal.is-a.dev/blogs/centroid-decomposition/https://akshataggarwal.is-a.dev/blogs/centroid-decomposition/Divide and conquer on trees: centroids, centroid trees, and path queries.Sun, 26 Jun 2022 00:00:00 GMTCPdsaHow do you find the diameter of a tree?https://akshataggarwal.is-a.dev/blogs/tree-diameter-and-center/https://akshataggarwal.is-a.dev/blogs/tree-diameter-and-center/Tree diameter via two BFS runs, counting diameters, and finding the center — with proofs.Sat, 25 Jun 2022 00:00:00 GMTCPdsaWhy do we need Fenwick trees?https://akshataggarwal.is-a.dev/blogs/fenwick-tree-notes/https://akshataggarwal.is-a.dev/blogs/fenwick-tree-notes/Prefix sums with point updates in O(log n): how the Binary Indexed Tree earns its keep.Sun, 19 Jun 2022 00:00:00 GMTCPdsaHow does a segment tree work?https://akshataggarwal.is-a.dev/blogs/segment-tree-notes/https://akshataggarwal.is-a.dev/blogs/segment-tree-notes/Build, query, and update a segment tree for range sums, with diagrams and C++ you can steal.Thu, 17 Feb 2022 00:00:00 GMTCPdsaHow does Dijkstra's algorithm work?https://akshataggarwal.is-a.dev/blogs/graph-shortest-paths/https://akshataggarwal.is-a.dev/blogs/graph-shortest-paths/From BFS on weighted graphs to Dijkstra, multisource Dijkstra, cycles, and spanning trees.Sun, 10 Oct 2021 00:00:00 GMTCPdsaHow do you store and traverse a graph?https://akshataggarwal.is-a.dev/blogs/graph-representations-and-traversal/https://akshataggarwal.is-a.dev/blogs/graph-representations-and-traversal/Representations, DFS, BFS, connected components, and multisource BFS — with C++ and dry runs.Sun, 26 Sep 2021 00:00:00 GMTCPdsa