Create working-schema views over <persist_schema>.barriers

Emits per-species + per-source views in the working schema that filter the unified province-wide <persist_schema>.barriers table (link#152). Each view exposes the bcfp-shape <table>_id column lnk_pipeline_access() expects (barriers_bt_id, barriers_dams_id, ...) so the existing barriers_per_sp + barrier_sources consumer code paths run unchanged.

Usage

lnk_barriers_views(
  conn,
  schema,
  cfg,
  species = c("BT", "CH", "CM", "CO", "PK", "SK", "ST", "WCT"),
  barriers_table = NULL,
  recreate = FALSE
)

Arguments

conn: A DBI connection.
schema: Working schema name where the views are created.
cfg: An lnk_config object (resolves cfg$pipeline$schema for the underlying persist-schema reference).
species: Character vector of species codes the views should cover. Default c("BT","CH","CM","CO","PK","SK","ST","WCT").
barriers_table: Character or NULL. Source barriers table the views read from. Default NULL → uses <persist_schema>.barriers from cfg (the original behaviour). Pass a working-schema name (e.g. paste0(schema, ".barriers")) to build the views over a per-WSG working table — used by lnk_pipeline_run()'s mapping_code phase, which runs BEFORE the per-WSG persist write so persist barriers may not yet hold current data. Tunnel-free / link-canonical either way (the underlying table has blocks_species from lnk_barriers_unify()).
recreate: Logical. FALSE (default) emits CREATE OR REPLACE VIEW only. TRUE restores the historical DROP VIEW IF EXISTS + CREATE OR REPLACE VIEW pair — needed only when a view's column shape has changed, since CREATE OR REPLACE may not rename, retype, reorder or drop an output column. See Details for why the default changed (link#250).

Value

invisible(conn). Side effect: creates or replaces two views per species (_unified + _access) + three source-typed views in schema.

Details

The views point at the province-wide table — cross-WSG dnstr walks resolve correctly because fresh::frs_network_features() walks FWA topology and reads from the view (which is the unified table). Fixes the PARS BT 60% defect (PARS drains through dams in PCEA / UPCE WSGs) and unblocks any regional run.

Per-species views (two per species bt, ch, cm, co, pk, sk, st, wct):

<schema>.barriers_<sp>_unified — filtered by '<SP>' = ANY(blocks_species) (ALL barrier families incl dams). _unified suffix avoids name collision with the per-WSG <schema>.barriers_<sp> tables that .lnk_pipeline_prep_minimal builds for the break-time path.
<schema>.barriers_<sp>_access — the per-species accessibility set that drives accessible in mapping_code (link#200). Reproduces bcfp barriers_<sp>: NATURAL barriers only (barrier_source IN ('GRADIENT','FALLS','SUBSURFACE_FLOW') — the gradient-at-species-threshold is already encoded in blocks_species) MINUS the observation/habitat override (anti-join barrier_overrides), ∪ all USER_DEFINITE (override-exempt). Dams/PSCIS/modelled are excluded — they annotate token2 via the per-source views, never block access. Same feature shape (barriers_<sp>_access_id + ltrees + geom) so lnk_pipeline_access() / fresh::frs_network_features() consume it unchanged. See RUNBOOK.md §5.

Per-source views (matching the bcfp source-typed tables consumed by the barrier_sources arg of lnk_pipeline_access):

<schema>.barriers_anthropogenic_unified — barrier_source IN ('PSCIS','CABD','MODELLED').
<schema>.barriers_pscis_unified — barrier_source = 'PSCIS'.
<schema>.barriers_dams_unified — barrier_source = 'CABD'.

(Remediations stay sourced from <schema>.barriers_remediations built by lnk_barriers_emit() — they're consumed by the remediated_dnstr_ind path which joins to <schema>.crossings directly, not via the unified barriers table.)

Reruns are safe: each view is emitted with CREATE OR REPLACE VIEW, which is atomic — a concurrent reader sees either the old definition or the new one, never nothing.

Until link 0.47.3 every statement was preceded by DROP VIEW IF EXISTS. Each statement autocommits, so that pair left a real interval in which the view did not exist, and a concurrent fresh::frs_network_features() walk could fail with relation ... does not exist. The DROP was belt-and-braces from the function's first commit rather than a fix for anything, and the view column list has not changed since, so CREATE OR REPLACE alone is sufficient. RUNBOOK.md §6 records the DROP's cost in the sequential case as well: an orphaned backend holding a lock on barriers_bt_access blocked every later DROP VIEW indefinitely.

If a future change alters a view's column shape, CREATE OR REPLACE will fail and the error names recreate = TRUE. That is deliberately not an automatic fallback — silently reverting to DROP + CREATE would reintroduce the window at the worst moment, part-way through a parallel recompute (link#250).

The underlying <persist_schema>.barriers table must exist — typically initialized by lnk_persist_init() and populated by lnk_barriers_unify()

lnk_pipeline_persist() for all WSGs in the regional scope.

Examples

if (FALSE) { # \dontrun{
conn <- lnk_db_conn()
cfg <- lnk_config("bcfishpass")
loaded <- lnk_load_overrides(cfg)

# ... lnk_persist_init + lnk_pipeline_* + lnk_barriers_unify +
#     lnk_pipeline_persist all already run for all WSGs ...

lnk_barriers_views(conn, schema = "working_pars", cfg = cfg)

lnk_pipeline_access(
  conn,
  segments        = "working_pars.streams",
  aoi             = "PARS",
  barriers_per_sp = setNames(
    paste0("working_pars.barriers_", c("bt","ch","cm","co","pk","sk","st","wct"), "_unified"),
    c("bt","ch","cm","co","pk","sk","st","wct")),
  barrier_sources = list(
    anthropogenic = "working_pars.barriers_anthropogenic_unified",
    pscis         = "working_pars.barriers_pscis_unified",
    dams          = "working_pars.barriers_dams_unified",
    remediations  = "working_pars.barriers_remediations"))
} # }

Create working-schema views over `<persist_schema>.barriers`

Usage

Arguments

Value

Details

See also

Examples