GM_Segment Table

The GM_Segment table stores the individual shared DNA segments between two GEDmatch kits. Each row is one matching segment on one chromosome, with its start and end positions, length in centimorgans, and SNP count. These segments are the detail that adds up to the totals on GM_Match and feed the chromosome browser.

GEDmatch gathering is currently unavailable in the Client and is expected to return in a future update. This page documents the schema and the behavior of the existing gather code as written.

kita and kitb

kita is your (primary) kit and kitb is the match kit. Segments are stored bidirectionally: for every segment, the gather code writes two rows — one with kita = your kit, kitb = the match, and a second with the roles reversed. This lets queries find a segment from either kit’s perspective. Inserts are de-duplicated on the combination of kita, kitb, chromosome, and p1.

How It Is Populated

Segments are written from the segment-search results and from AutoSegment / cluster nodes that carry embedded segment data. Each source provides chromosome, start and end positions, cM, and SNP count; both directions are inserted.

Column Reference

Column	Type	Description
Id	int (PK)	Auto-incrementing primary key
kita	string	Your (primary) kit number. References `GM_Kit.kit_num`.
kitb	string	The match kit number. References `GM_Kit.kit_num`.
chromosome	int	Chromosome number the segment is on.
cm	decimal	Length of the shared segment, in centimorgans.
p1	int	Segment start position (base-pair position on the chromosome).
p2	int	Segment end position (base-pair position on the chromosome).
snps	int	Number of SNPs in the matching segment.
created_date	string	When the segment record was created.

Related Tables

GM_Match — the kit-to-kit summary whose shared / largest totals these segments make up.
GM_Kit — resolves kita / kitb to people.
GM_TriangulatedSegment — overlapping segments grouped into triangulated clusters.