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Report From: Delphi-BCB/Database/Core VCL [ Add a report in this area ]

Report #: 75575

Status: Open

Suggestion to improve TDataset.FindByName performance

Project: Delphi

Build #: 21218

Version: 12.1

Submitted By: Mason Wheeler

Report Type: Suggestion / Enhancement Request

Date Reported: 7/6/2009 5:30:56 PM

Severity: Commonly encountered problem

Last Updated: 3/20/2012 2:24:39 AM

Platform: All platforms

Internal Tracking #: 278628

Resolution: None (Resolution Comments)

Resolved in Build: : None

Duplicate of: None

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Description

TDataset.FindByName is well-known for its slow performance, especially in loops. Every time it's called, it runs a (slow) linear search, doing a (slow) string comparison against every field name until it finds a match. It's bad enough that it's become a common design pattern to preallocate local TField variables in functions that have to use FindByName, so the call will only have to be made once for each field.

This overhead could be alleviated quite a bit by replacing the linear search with a hashtable lookup. Add a TDictionary<string, TField> to TFields, and have TFields.FindField check it. Make sure to uppercase all the strings first, to preserve case insensitivity.

Suddenly instead of a slow string comparison multiplied by a slow O(N) search, we have a slow string-hashing operation multiplied by a much faster O(1) search.

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